Unless the m4a files are ALAC-encoded, you shouldn't do it. m4a files tend to hold AAC-encoded audio, which is a lossy format. Opus is also a lossy format, so you'll only lose sound quality, basically. You should only convert lossless to lossy.
No clue why it isn't on there, but bsnes is available as part of higan, ares (kinda?), standalone, or as one of many bsnes RetroArch cores (bsnes-mercury is generally the most recommended from my experience).
ETA: If you're not into RetroArch, I'd highly recommend ares.
These entities all have similar names and share similar origins, having been started by the founders of Open Collective and incubated in the Open Collective ecosystem, but are independent nonprofits with their own budget, accounts, staff, board of directors, and mission. They each have a separate commercial relationship with Open Collective. [emphasis not mine]
Open Collective, Inc. seemingly has nothing to do with OCF shutting down and neither entity has claimed anything to the contrary.
Though I have yet to try Guix, I think I'd move over to it if they adopted something similar to flake support. The idea that it uses a non-arbitrary language for declaration is very appealing to me. Do you know if it's simple enough to get non-free kernels, though?
Plasma and GNOME are two completely different projects made by completely different organizations made on completely different technologies with completely different philosophies. That would be like proposing that McDonald's and Wendy's merge.
Yes, open source development isn't necessarily as efficient and doesn't lend itself to as nice of UX/UI/etc, but that's not the point. The point is the freedom. Do I wish, as a GNOME user, that GNOME had certain features that Plasma does? Yeah, but part of the reason I like GNOME is that they're so stringent about what makes it into the DE that it makes for an infinitely more polished experience than Plasma. You can definitely approximate the GNOME workflow on Plasma well enough, and that's the great thing about Plasma: you can do almost anything you want with it.
You're not the first person to propose that open source projects merge, and you certainly won't be the last, but freedom also implies that you work on what you want to, so let people work on what they want to!
BTW, there are certainly more DEs than just GNOME and Plasma. Maybe try Budgie! It's like the default workflow of Plasma mixed with the simplicity of GNOME.
I don't really have anything notable or profound to add. I just want to say that, setting all controversy aside, RMS is a titan, an icon, and a living legend, and I'm so happy that his treatment is going well. Here's hoping that he and his beard make a good recovery and he's around for a while longer.
That's actually why I went vegan: I couldn't see myself ever killing an animal.