OpenDOAS has actually had the OpenBSD-specific code removed (https://github.com/Duncaen/OpenDoas/commit/74449f015ff7a7230...), and replaces some of the doas mechanisms that rely upon OpenBSD to work with sudo-like flag files and suchlike.

There are, moreover, 2 ports of doas to other systems. OpenDOAS is one. Jesse Smith's https://github.com/slicer69/doas is the other. The latter retains the OpenBSD-specific code, and is the more portable of the two at the expense of only doing everything that the tool is capable of when actually built on OpenBSD.

Most use cases can be paved over with alias. "alias sudo=doas" or "alias doas=sudo"

I don't understand the muscle memory relevance?