

I can’t say whether it can be cleanly migrated to another app but there are a number of export options to get you either to plain Markdown or something else within reason. When using the export option, the resulting Markdown at lest gives relative paths to any included media.
I don’t think it’s fair to suggest it’s not using Markdown. It just has a wrapper around it to make it work better for the usual use case of being a digital workbook.
I can’t speak to Arch but I use Ubuntu every day. I hate on Ubuntu because I use it every day. They make terrible choices. They’ve got common, serious issues people have reported at least as far back as 2009 with no acknowledgement or plan to address. I’m on LTS and they push through multiple reboot requiring sets of updates a week, heedless of the impacts.
I don’t feel like learning a totally new environment so I’ll be switching my main computer to Mint whenever I get the time. So I can deal with someone else’s annoying decisions for a while.