Recalbox has Moonlight installed which allows you to share a desktop PC to an RPi. It’s an NVIDIA technology and so, for a Linux host-side, you’ll need to use the open source software Sunshine.
In addition to running sunshine, check out this fix I noted at the bottom. There are some parts of the game discovery process that aren’t working with the current script in recent Recalbox versions - not tested on the latest 8.1, however. Once you get this working, an entry for Moonlight will appear in the Recalbox main interface automatically.
But, with all that above, it definitely does work. I’ve run Linux host -> RPi4 over wifi and it worked fairly well. You can check the Recalbox wiki moonlight page for more details, tips, etc. I remember having some minor difficulties getting sunshine to run at the time.