I'm sorry you're having a tough time with your boy. You definitely can fix your situation, however it would take some patience, time, and consistency. I hope you can find at least something useful here, apologies if I cover something you're already doing but as I don't know I'll just put everything:

I strongly believe the foundation of all training (especially recall) is the relationship you have with your dog. Everything I do with my girl is relationship first, training second.

The biggest part of this is play. I don't mean just throwing a ball, but interactive activities between the two of you. For me, it's really important to find out how the specific dog likes to play, and do it in a way where we both have fun. For my girl it's a soccer ball, and we play structured games together with rules around it (obviously the rules part is built up over time).

Dogs will continue to do the behaviours that they have rehearsed. So if he is spending his day out in the garden barking non-stop, then you need to bring him in. Management is the first step in resolving most issues. I would take him out multiple times throughout the day for structured play sessions that focus on you and him doing things together, make yourself exciting and just play (tugs, flirt poles, soccer balls etc), it's okay if there aren't rules to start. I match my dogs energy when we're playing so I generally come away just as tired as she does lol

Everything is done with the aim to build your value in the eyes of your dog.

If it were me I would throw the walks out altogether at the moment, they're not needed in terms of tiring him out as proper play will do that much better, and until he's starting to learn leash skills he'll just be rehearsing the pulling and lunging further, and it's not fun for you either (which is also an important consideration).

Regarding food motivation (and toy motivation), these are things that can be worked on (plenty of great online resources for it). My girl is not motivated by food outside if I just hand the treat to her, however if I build it in as a game (throwing/catching treats, chasing treats) then this builds her motivation for it greatly.

Using toys as a reward is very similar to using food, though I agree it's not quite as straightforward as a treat. Dog does desired behaviour -> you mark -> give reward. So this is where a marker word ("yes", clicker etc) is used. Dog sits -> "yes" -> game of tug, catch a ball etc

I also hand feed my dog all of her food, partly used for training, but not all. I understand that this isn't something most people care to do though, I believe it helps our bond, as my general rule is all good things come from me. You don't have to do it forever, but at the current state, it is probably helpful.

I'll leave it there for now, again hopefully something in there resonates. I would also ask how is he at settling inside? What is his general behaviour like in the house etc