As far as I'm aware, alpine isn't designed for regular use, but as a minimal distro for container environments. Of course there's technically nothing stopping you from using it on a desktop but you're likely to be on your own in terms of support

Oof. You may want to rethink Alpine as a desktop if you're not familiar with how to debug it. You are in for a world of shuffling back and forth haha.

Alpine was originally meant for embedded devices to have a super tiny static footprint, hence it being based on busybox. APK as a package manager coupled with using dotfiles as a configuration language is always going to leave you second guessing whether something got missed, and questions like you're asking.

I would go back through the dep chain and make sure EVERYTHING is actually installed AND configured/linked. Even on image builds I've seen APK silently miss a dep due to a resolve error and continue. It's not built to be as thorough as something like rpm or apt, and it's very easy for something to get completely missed or just not configured or linked.

Good luck!

What is the output of swayidle -d and from loginctl?
You may not be running within an elogind session which could explain the unknown session error.