Flatpak Nix solved most of the issues I had the last time I tried musl. It's working fine as of today!
EDIT: Flatpak refuses to work with xdg-desktop-portal when dbus is running, so now I'm using the Nix package manager. Void+Nix is a match made in heaven!
New to linux. I tried this same thing in a virtual machine. I got a lot of stuff to work, but it seems like any services and daemons have to be installed on xbps because the ones from nix can't be enabled for Runit, or at least require doing that in a different way. So I would install those services through XBPS and everything else with Nix-Env which was enough to get a WM up, but I kept running into issues installing other things.
Now I'm running Void directly on my computer and I'm sticking to XBPS and so far it has gone a lot smoother, but I've heard about this Void + Nix thing a lot, but never really seen mentioned what the recommended approach to that is
I'm not sure what the general consensus is, but I've been using XBPS for everything, and then nix-env for anything not available on the default repos or in srcpkgs. On my system, it's essentially just a replacement for Flatpak and AppImage, as I've had trouble running Flatpaks on Sway, and AppImages aren't yet supported on musl libc.