

Hdcp bypass splitters seem easy to find, have you tried one? There are also hdcp converters so if you have a splitter that only bypasses 1.4, you can try hooking it up to a 2.whatever to 1.4 converter.
I also can’t remember how they work exactly but you might need an hdcp compliant display connected to the main output of the splitter so the CC can establish an hdcp handshake. Idk if that’s only a thing with some of them. Good luck!
FYI the codename for the Xiaomi Redmi Note 13 5G is “gold”. You’ll usually see stuff for your phone labeled with that codename since it’s much shorter and easier to check than the whole name where you have to check pro vs non-pro, 5G version, etc as other variants will have completely different codenames.
If roms don’t have official support, then basically your other main option is to look for unofficial builds made by random people on XDA. I’ve used unofficial builds for many years in the past and they’re generally fine, but it’s up to you.
I don’t see any rom threads in the XDA forum for gold, so unfortunately I can’t really help any more. Good luck!
(Skimming around the XDA threads, it appears that the lack of roms is due to mediatek not releasing necessary source code, so if you want custom roms, it’ll be a lot easier to find them for a different phone)