The Flatpak is already packaged and works well. It just needs to be maintained from a person that joins the Inkscape community.
This would allow further improvements like Portal support and making the app official on Flathub.
Update: One might have been found!
Usually if the appimage has a github release with a zsync you have that verification.
I don’t use gearlever, as far as I know gearlever doesn’t even let you sandbox the appimage like AM does. I don’t think any of those forces signature verification besides AppImageUpdateTool and that’s because that’s part of the zsync update process.
Interesting, will look into this. The issue is of course that these tools are optional.
But if they work, they may fix nearly many issues. Some will remain, for example many proprietary apps dont use Github releases, while these may be especially targets of fakes.