Yes, and I think its fair to assume that some backend to execute the x86-64 Linux ABI will out-live most readers.
Projects like https://justine.lol/ape.html, https://guix.gnu.org/manual/en/html_node/Invoking-guix-pack.... or https://github.com/matthewbauer/nix-bundle do make it approachable to "bundle" a lot of software down to libc.
It's not hard, and the benefits go far outside merely supporting Nix, as e.g. a flake.nix file would allow this project to generate docker images, and appImage images, as basically afterthoughts. (See e.g. https://github.com/matthewbauer/nix-bundle.)
Nix flake support would also provide a perfectly reproducible build environment, which can help clarify dependencies, and thus help the project build achieve idempotence, but I'll save the full shill for some github issue.
In fact, I'm inclined to roll up my shirtsleeves and help make this real, at least for Thunderbird.
PS. there is also the fact that the Thunderbird provided downloadable tar.bz2 is not usable under nix, which makes this problem more pressing.
PPS. Yes, I know about steam-run. Which, btw, works here. All the same, weird that I have to go get some random steam-related thing to make thunderbird happy, right? https://unix.stackexchange.com/questions/522822/different-me...
Though, here is e.g. https://github.com/matthewbauer/nix-bundle, which is supported as an experimental command in nix 2.4.