is there a way to install python3.9
No. You should message @glitch_support for that.
No, but you could suggest it in #feature-ideas for support to see.
Yes but it’s quite knarly
Provided the small amount of packages needed for it are installed (kinda high probability I think) you can compile from source though this can be horribly slow.
Replicate an environment similar to glitch and copy the python binaries over after installing locally OR compile it statically linked.
Only problem is space, and once the container restarts then it’ll go back to the original version