If you can afford it, I'd go the sedation route due to the time-pressure. This way, you'll have a perfect starting point - and you can go from there.
My dog was the exact same way. I adopted him at 8 months old and it took about a year to get him comfortable enough to have his nails trimmed - with two of us doing it (one providing pieces of sausage, one doing the clipping).
I thought he'd never get used to it, but he did. Started with touching the paws, as you've done, until he was totally comfortable with that. What I found helped a lot was not only doing "sessions" with treats, but also just making paw-touching a natural part of cuddling and stroking him. Then from there, started giving him an evening grooming session - brushing, checking ears, checking paws, touching his nails, pushing the fur back between his toes, etc. This all took time! Months, easily.
From there, I started desensitising him to the clippers themselves. Just having them out on the table during his grooming. Then the next week, holding them in my hand and putting them down. Just making it all really chill. Spent weeks just touching his paws briefly with the clippers still on the safety latch.
Eventually worked up to being able to do one of his dew claws. Then worked up to doing one claw every night. And now can do all of his claws in 1-2 sittings.
Have a look on YouTube if you're struggling, and just keep going, slowly but surely!
The important thing is to make it as relaxing as possible for you and him. If it takes a year, it takes a year.
My dog is an anxious rescue and has been super slow to desensitise to anything - muzzle, nail clipping, ear examination, even grooming. But if you persist, you should eventually get there!