Quick note to self.

Printing from Android requires IPP. If your printing does not support this protocol out of the box you will not be able to directly print from Android devices.

CUPS can then be used to translate between IPP and JetDirect (in my case). Install and configure CUPS and then on Android configure the printer. The later means connecting to a printer by IP address. In that form enter the following:

<ip-of-your-printer>/printers/<your-printer-name>

The way Android presents it, it seems only an IP address or hostname is allowed, but “no”, you can sort of put an URL there.

Helpful other things: debug logging in CUPS: cupsctl --debug-logging