Some of the features of the port:
software rendering with support for several resolutions, up to 1280x720;
sound (but no music yet);
supports the Mission Packs and other mods compatible with vanilla Quake, with a simple mod selector menu;
analog controls and shit.

To install it, just unzip to the root of your SD card, then copy pak0.pak and (optionally, if you have the full version of Quake) pak1.pak from your Quake installation to /switch/nxquake/id1/. You can then run the game using the Homebrew Launcher. You can get pak0.pak from the Shareware Quake data files in attached to this message.
If you want to play Mission Pack 1, copy hipnotic/pak0.pak to /switch/nxquake/hipnotic/ from your installation.
If you want to play Mission Pack 2, copy rogue/pak0.pak to /switch/nxquake/rogue/ from your installation.
For any other mod, just copy its folder to /switch/nxquake/.

Some notes:
if it crashes and exits back to HBL/Horizon silently, check /switch/nxquake/error.log to find out what caused it;
better exit the game using the Quit option in the menu, don't just press the Home button, use Y to confirm the exit prompt;
multiplayer doesn't work yet, but probably will be added later;
port is pretty barebones, so if you have any suggestions, please post them here or in the Github issues.

Kevin Shanahan (aka Tyrann) for TyrQuake;
Rinnegatamante for some input-related code I copypasted from vitaQuake;
some nice people from the ReiSwitched Discord for testing (especially Drakia, Crusatyr and Patrick);
id Software for Quake.