Waydroid on linux comes to mind. It sort of semi worked out of the box on archlinux but I can't try to imagine setting up somewhere else..

Wait a minute, while writing this comment, I realized that there was a guy who sort of packaged waydroid into flatpak-ish to run android apps in flatpak.

https://flathub.org/en/apps/net.newpipe.NewPipe

(It uses android translation layer??)

I am not an EU citizen but if somebody is & they want this age verification app on desktop, maybe the best way might be to support this android translation layer to convert this EU app into something that can run through flatpak and then use linux I suppose.

I mean, some of y'all are so talented that I feel like surely someone would do it if things do go this way! So not too much to be worried about I suppose :>