This may not be what you want to hear, but I think the very best thing you can do is change your expectations and negative narrative.
Change your negative narrative:
"ds has always been a crap napper"
To positive self-talk:
"DS has made great progress towards independent sleeping in 7 months. I have done a great job in teaching him using gentle, kind methods without creating any distress"
I don't want to keep doing this as it's so exhausting
This could also be negative self-talk. It doesn't need to be exhausting having to resettle back to sleep. You could just take the 5 minutes it takes to resettle, not attach any anxiety or sub-text to the need to resettle, just see it as 5 minutes then carry on with what you were doing.
Do you have another child or responsibility needing your time? If not, then if you find waiting to resettle exhausting, lie on your bed while waiting to resettle. That's calm and relaxing then.
This has a lot to do with expectations too. Leaving him (as you mentioned trying) isn't going to work. He will need you to help him settle for a long time yet. But as you make more progress, he will need fewer resettles. Don't get anxious that you need to do 2 or 3 resettles, be thankful you don't need to do 4 or 5. Know that in time youll only need to do 1 or 2. Then sometimes you wont need to do any.
I assume you are establishing tools for independent self-soothing - comforter, dummy etc?
Its usually after 12 months before baby really bonds with a comforter, so start feeling comforted to snuggle into their special thing. So you have a while yet before baby can learn this. Dummies are quicker to establish, but you still need to do dummy reinserts until baby has the skills to do this himself.
Really - just relax, accept the sleep situation as it is and keep making those changes and progress towards independent sleep.