We just moved from NYC to a suburb and my 10 yr old is now learning to ride a bike. It's been ok, but he's getting frustrated that he isn't picking it up so quickly - no training wheels, he's really just getting the hang of balancing and coasting before pedaling. I pushed him to try today when he didn't want to and he quit in frustration after 15 minutes and says he doesn't want to ride, that he doesn't like it. I feel like this is a skill he should master but don't want to push him so hard that he hates it. Any pearls of wisdom??

Outsource it. Rei has classes.
hire someone to do it- the dynamics between you two probably dont work to be able to do this
I don’t think you have to outsource this. Is the bike a decent bike? If it’s a crappy bike, consider borrowing a better one for him to learn on. Make sure the seat is low enough that he can put his feet flat on the ground. You can also take the pedals off completely so that he is gliding, but make sure you know how to put them back on. For most kids, it is harder to get going than to keep going, so making sure he can comfortably touch the ground will make him feel secure. Tennis courts (hard court) are great to practice on because they are flat. And good job for teaching him now, even though he is resistant. It is worth a little struggle to teach him now.
We did this exact thing with 9.5 yo DD this past summer. Like yours, she was very frustrated at first. We basically did 15 minutes per day for about a week. Positioned seat so that DD's feet could touch the ground, but not too low that legs were too bent (can't get much momentum if legs are too scrunched up). DD controlled the entire thing (i.e., we didn't hold back of seat or anything like that). DD just would pedal, try to balance, tip, and try again. After a week or so, DD got the hang of it (and she is not athletic and actually was nervous about falling at first). Once it clicked, she was able to get going pretty quickly. A couple weeks after figuring it out, she was riding with us on 10-mile plus rides. I was amazed (especially after how frustrated she would get when first trying and wanting to give up).
Coasting for longer and longer periods on a strider bike (no pedals). Pedaling isn’t the hardest part. It’s balancing. My kids both had success w this method at age 3. Make sure bike is appropriately sized. Sounds like he’s very close!
Get a Woom bike, they are very specifically designed to make riding great and easy for kids. Ours was riding on her own in 10 minutes.