Yes. I did something very similar with my old binary rpm Sigil package. I ended up having to go pretty far down the rabbit hole of extra libs that needed to be included (and sometimes built with alternative configs to keep them from pulling the kitchen sink along with them) and still ended up with a version of Sigil that couldn't support sound/video. I drew the line at building/delivering gstreamer plugins with questionable licenses.
I'd need to do some testing to see what all would need to be shipped in the image to have a fully working Sigil. And nothing short of a fully working Sigil with Qt5/Python versions that match the Windows/Mac packages would make sense to me. I don't think I'd try to tackle it without using linuxdeployqt to create the AppDir and/or the AppImage, though. It uses appimagetools.
Knock yourself out if you've got something you can use to create a test package. I probably won't be able to dive in before the weekend.
