Run Termux itself in PRoot

[jace]

Can I run Termux entirely in a PRoot? I have these recurring problems with no good solutions:

1. Neovim LSPs download NodeJS modules, which then fail to run because they all have #!/usr/bin/env. I have termux-exec installed and $LD_PRELOAD pointing to it, but it doesn't seem to work in this case. I have to do a periodic termux-fix-shebang after auto-updates.

2. I use Syncthing to sync folders from my laptop. Sometimes these have Python venvs in a .venv folder, which obviously won't work in Android because the binaries are different and there's no +x bit. I can tell Syncthing to skip the .venv folder, but I can't symlink it to a folder inside Termux because shared storage can't have symlinks either.

What if I run my entire Termux environment in a PRoot? I can then mount $PREFIX/* folders directly to /, mount local venvs into each of the Syncthing shared folders, change my username into something better than u0_a<random>, and there's no more termux-fix-shebang required.

How badly will this clobber performance? I can do this from inside my login shell, but can I make Termux do this before the shell?