In my experience, random non-whitelisted indie games work pretty great. My guess is that the average small shop is using more 'default' tooling with less custom engine stuff, meaning things are more likely to work under proton out-of-the-box than a giant AAA megabeast.

(I've had very similar experiences in a very different context with OEM Android. Small manufacturers don't screw around with the OS internals, while big shops (eg, the one rhyming with HamStrung) are more likely to change things in non-obvious ways.)