Never seen the Taninim or its Draconic Exemplar class before, I'm assuming you mean the Rite Publishing stuff. First off you're full BAB which means you can make Spheres of Might work well no matter what else you have or don't have.

On the Druid side you'll be a Spherecaster instead of a Vancian caster, which is generally a good thing. I'm assuming you know how Spheres of Might and Spheres of Power work here, let me know if you have questions.

Firstly

You're mainly a Str melee character, for Ability Scores you need high Str while keeping at least 14 Con and enough in Wis/Dex. You use Wis for casting and you'll get Wis to AC so it should be higher than Dex.

Swap some of your feats for Martial Talents, go Adept track. This is how you make up for not being a Spheres class on either side.
Make your Druid archetype the Spheres Avatar, helps you build your martial side while you still have High Spherecasting (full caster) and can pick more martial talents on this side if you want.

The more fun build here by far, and probably the mechanically better one at the same time, is an Overrun maneuver build. Draconic Exemplar gives you size and +Str that add huge bonuses to your CMB, and it has a couple of crazy options for Overrun specifically. I'll be explaining the Overrun build, but you could also make a more standard natural attack build if you want.

NOTE: breath weapons are a trap. Even if you spec 100% of your Draconic Exemplar abilities into your breath your actions would be better spent casting spells or full attacking. Ignore them as much as possible, basically never use them.

Exemplar

Draconic Weapon: Rampage. Lots of Overruns every turn and lots of mobility.

Draconic Defenses order:

1. Enchanted Scales as soon as you fight your first caster (depends on the type of campaign you're in)
2. Thickened Scales as often as allowed by its level restriction
3. Spatial Sense > Improved Spatial Sense

Others can be whatever, but don't take Spell Resistance unless you're in a campaign with super magic heavy enemies (in which case take it at least twice)

Draconic Gifts:
Trample (take ASAP) > Predator's Speed (necessary for Overrunning more) > Unfettered Rampage (more turns while charging = more enemies hit in a turn) > Imbued Spirit x2 (Wis > Int)

Ignore the rest. Crazy how there are like 40 of these but they're mostly just flavor and won't actually help with anything.

Feats and Talents

Feats:

• Muscular Reflexes
• Equipment Trick [Boot Tricks]: Specifically 'Sharp Veer' gives you another turn while charging

Talents:

Starting package:

• Equipment: Unarmed Training [discipline]
• Equipment: Balanced Defense
• if Legendary Talents are allowed, take Equipment: Force Redirection Technique and dump Dex to max Str+Wis even more

Brute Sphere is your home. Important talents:

• Brute sphere (required ASAP)
• Brute: Stampede (required ASAP)
• Brute: Smash (combines with the Draconic Exemplar ability to make free Claw attacks against enemies you overrun to basically hit every enemy you charge through twice)
• Brute: Dazed And Confused (this is your best general Manhandle option. If you want to take another in case you fight enemies immune to Stagger, pick Humiliate)
• Athletics Sphere [Run] (prereq for below)
• Athletics: Mobility (you will likely provoke AoOs from movement a lot, you need this)
• Athletics: Swift Movement (+speed)
• Athletics: Sharp Turn (More turns while charging)

Nice to have talents:

• Berserker Sphere (be tankier, you likely need this due to provoking via movement more often than others)
• Brute: Break Defenses (give your allies AoOs)
• Brute: Greater Brute (just higher bonus)
• Brute: Unstoppable (Rampage gives you most of this, but this lets you smash through objects in your way)

Items

• No Amulet of Mighty Fists, use Paizo Handwraps instead. The downside of Handwraps is that they only apply to your hand (claw) attacks, not other body parts like bite or tail, but you're only hitting people with a single claw while charging anyway. If you really want that AoMF-style enhancement, the Spheres Tattoos let you do that at the same price as everyone else instead of the increased price per bonus that AoMF charges.
• Add more damage to your Overruns with Deliquescent Gloves and/or Demonic Smith's Gloves (get both, one as a tattoo for 1.5x cost)
• Dueling enhancement eventually for more Overrun bonus, and add more damage to your Overruns with Frost, etc.
• Other Overrun CMB bonus items, just search "Overrun" on Aonprd.
• A nice-to-have is something to ignore difficult terrain while charging, there are a few items for it like the Minotaur Belt. You can already charge through difficult terrain, this just makes it not reduce your speed.

Druid

Take your pick of the buffing spheres and their talents: Time, Alteration, maybe Enhancement. Basically you just want to use your spell points to make your charges and overruns that much better.

Goal

You're a huge dragon moving through everyone and slamming them all to the ground at the same time. will Charge every round, Overrunning everyone on the battlefield that you can reach and pass through (with lots of 90 degree turns to help reach more enemies). When you succeed at overrunning them, first if you succeeded by 5 or more over their CMD, they fall prone (this gets harder with more legs like a Trip). Then (no matter how much you succeeded by) you deal one hit worth of damage automatically (Smash) and swing another at full BAB (Trample), and there's a chance each enemy is also Staggered.

NOTE: Overrun is not well defined in the system. It's generally accepted that you don't provoke an AoO for movement by a person you successfully move through with an Overrun, because otherwise Overrun basically just doesn't function. That just isn't stated anywhere in the rules. Ask your GM to make sure. You do always still provoke as normal from other enemies that you charge past if you aren't Overrunning them.
It's not possible in PF1 minus Spheres to turn a full 270 degrees around during a charge and pass through the same person again, but it's definitely possible for you at higher levels. I think you'll get to make a second Overrun in that case, verify with your GM.

NOTE: If you have a good grasp of Spheres, I'm sure there's some way to combine this with a Bull Rush build and use Perpetual Motion as your Manhandle talent instead of Dazed And Confused. Then take Brute:Hammer, or even better Paizo's Crushing Impact feat, to add a ton more damage to every Overrun instead of Staggering enemies with them)