Hi,
The altera_remote_update_core.v is the core file of the Remote Update IP which can't be simply modified.
The RSU internal circuity can be used in Quarus Prime Lite edition as well. I think the options under the Assignments tab 'Greyed' out due to no project being opened. Please refer to this manual link https://www.intel.com/content/www/us/en/docs/programmable/683695/19-4-19-1-0/enabling-remote-system-upgrade-circuitry-61263.html, the devices available are Arria 10, Cyclone 10 GX, Arria II, Arria V, Cyclone V, Stratix IV, Stratix V, Cyclone IV, Intel Cyclone 10 LP
Thanks,
Regards,
Sheng