distrobox will give you access to the AUR and should be installable on any distro but the immutable/atomic approach might be worth looking into. I’ve been running bazzite on my personal machine and bluefin on my work machine for about a year now and it’s been great. the only snag is learning the order of operations for installing things without a reboot.
I am just one data point but both distros have been rock solid for me and half the time I don’t even realize updates had been run unless I see a new feature or something like that.
good luck on your journey!
i am unfamiliar with osprober but if you’re installing it from the AUR, it should be as easy as creating a distrobox container with arch as its base and running the installation command(s) from there, then a single line to export the command to your base system if you want to use it outside of that container.