While one of the nightlies shows "9.0.0 support" ReiNX apparently doesn't boot anyway because of a bootloader issue.
ReiNX officialy only works up to 8.1.
If you don't have a clean NAND backup, then even the Haku33 homebrew might not be enough to avoid a ban.
You can try of course, but be mindful that there is still a small risk.
Also, think about doing a backup right before using the tool,just in case.
Doesn't the DLC still get installed ? By just pressing "ok", Tinfoil should just keep running.
Also if you want to update and install DLCs you could use hgbshop to get everything you need.
There was a time where we were able to bypass the school's network using a VPN that wasn't blocked on the radar. Can't exactly remember the name, but I was able to watch YouTube.
One of the sites that weren't blocked on the school's network was some file uploading sites. I would upload some games, write down the URL and take it to school one day.