I see no point choosing M1 Pro over M1 Air as a dev machine. $300 extra buys you mostly the TouchBar.
Air has a better form factor (no sharp edge under wrists). Better keyboard (real top row). Both have essentially the same specs. Battery life on both is an overkill. Active cooling makes relatively small difference and kicks in only in long workloads (longer than a reasonable build should take).
As far as I can tell the Air and Pro get basically the same performance for the first 10 minutes. After that the Air will throttle. There is no task I would do that will max out the CPU for 10+ minutes so I don't see any reason to spend the extra for a slightly brighter (but otherwise the same) screen and two more hours of battery life (18 vs 20).
You may want to check the Activity Monitor to make sure the CPU is actually at 100% when you're doing that. Apparently it's quite easy to get the fans going on the Intel Macs even on lighter loads compared to the new M1 ones.
I use my computer mostly in the desktop mode with external screen, so I don't really care about screen quality, but I need certain mobility and I don't want mini.
Why go for Air tho ? Pro looks like a better device (better screen, better battery, same dimensions) and it's marginally more expensive.