used to be an indoor rabbit, has lived as an outdoor for over a year now: You will likely see a huge difference in his demeanor being indoors!
neutered: Since he’s neutered and an older bun, his litter box skills will likely get sorted out once he’s comfy w/ his new home
does not enjoy nail trimmed, brushing or being held (is it possible for me to socialize him?): Honestly, no bun enjoys this! Mine absolutely HATE it! You’ll learn tricks to the first two and you might eventually get to hold him, but most buns just don’t tolerate it. That doesn’t mean he might not hop on your lap or come to you for pets though!
independent; does not snuggle much (again, can I change that if I put some effort into it?): Again, even if he never snuggles, he might still love a good petting session!
The nice thing about an older bun–you’ll know their personality for the most part when you get them. And they are less likely to dig and chew! Bonus!
Sounds worth it to me