Much of crypto codebases are open source, where at the end of the day you're pushing to an OSS codebase.

If you're paid by a crypto co., foundation, grants, or are financially incentivized by your crypto holdings to contribute, you're often within the bounds of both OSS & crypto.

example: devs that've contributed to Defi projects e.g. uniswap, or received ethereum or solana grants for their OSS code (i think nearly everything user-facing in these organizations is OSS).