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!
Anything portable.
aisap uses bwrap it is mentioned in both links I gave you.
appman used to have firejail sandbox but it was dropped in favor of aisap because of that.