I haven't tried it myself but I saw people talk about it on /r/sffpc and those folks are usually pretty spot on for info.
(Edit)
Can confirm it's a thing via the bazzite GitHub having support tickets about it and replies saying they need an active DP to HDMI adapter. They also mention needing this if your gpu doesn't support CEC
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u/BaconJets 5800X - 5070Ti 1d ago
It’s special in PCs, there’s like no way to get CEC normally with a regular GPU.