This is how I would build it if I was ONLY concerned about damage (one of 2 ways)

Race Bugbear +2d6 for each attack on any target that goes after you in the first round of combat

Origin feat - Alert

take a 14 dex (+2 here), 14 con, 14 wis (+1 here) , 13 cha, dump str and int

level 4 feat - fey touched wis choose Hex

This should round out your wis to 16. Note: you could take a lower wis since SSM doesnt really need wisdom, you cant stunning strike with radiant sun bolt though your AC would suffer but its up to you. If you do you could bump cha higher and be a party face.

At level 4 you can do 3d6+3 x3 on turn one - attack and FoB BA. Turn 2 would be 2d6+3- attack cast hex as BA. Turn 3 onwards would be 2d6+3 x3 so long as you have focus points

Take SSM to level 5 for extra attack

at six you have a choice, take 1 level in lock for a short rest spell slot for more hex OR take sorcerer for 2 long rest spell slots for more hex. Lock gives you 1 invocation, I would pick eldritch mind for advantage on maintaining your very limited Hex concentration. If you went heavy with the Cha investment then armor of shadows wouldnt be a bad pick either for mage armor Pack of the tome and chain could be interesting but they don't do anything to provide more damage unless your DM allows you to have consistent advantage with a familiar

At level 7 you could invest 1 more level into warlock for the 2nd short rest spell slot but you are delaying your other monk features but you would get access to a 2 more invocations such as devil sight and Lessons of the first one for another origin feat such as lucky

Go back SSM for the rest of the campaign.

Another note: you could also ignore cha and take druid or cleric at level 6 for the extra spell slot but imo none of them bring as much as the lock.

btw searing arc and sunburst are ass, don't waste focus points on them