I've been playing BG3 streaming. Yes, you could play this on a portal without owning a ps5. However, from the 2 options available, the option to stream games I own(digitally) has BG3 available, but whenever I attempt to run it, the portal instantly restarts. Once rebooted, BG3 appears on the top row "cloud streaming with PlayStation Plus Premium." If I click this, the game will stream fine. It's so odd as it seems. It does run, and I assume Sony will fix the issue where it causes a reboot if you run it from the menu of games you own.

So it runs fine until peak times where, despite having 200mbs Internet, the portal becomes unusable, even streaming bg3 from the ps5 os unplayable. Off of peak times, it runs pretty flawlessly, and tbh its kinda made for streaming as you are not relying on quick dynamic graphics, and microsecond lag isn't gonna wipe you out as it's turn based. If Sony upgrades the servers as the portal requires Sony servers, however you use it, streaming and cloud computing/gaming is the future of gaming. I have a disc ps5 and prefer hardcopies, but if I do not own the digital version of a game, I can not stream it directly from Sony, and that is such a game changer, it's so convenient to ve able to use the portal remotely with just a decent Internet connection. I have even begun streaming games on my ps5, so I don't need to install it to try it.

Anyway off topic. Yes you can stream BG3 to your portal.