This got me 90 % of the way:
https://medium.com/@anzaloquin/how-to-configure-an-hp-scanner-on-ubuntu-overcoming-common-challenges-and-exploring-free-software-bf0a876cda07
the last 10 percent was getting the URI for my printer by running
$ scanimage -L
hpaio:/usb/HP_LaserJet_MFP_M28-M31?serial=##########
and then running
$ hp-scan -dhpaio:/usb/HP_LaserJet_MFP_M28-M31?serial=##########
which then triggered the HPLIP to install more software
and then I could get it to scan by running hp-scan just by it self – not sure if the URI was ever even needed.
$ hp-scan