@pair12 yeah i'm using a monitor from 2021 but it's nothing fancy, just an hdmi 1.4b connection with hdcp 2.2 and a lot of these cheap switches claim support for that (and more!) quite handily.
@mut @natalie yup also worth checking out System UI Tuner https://play.google.com/store/apps/details?id=com.bryancandi.android.uituner which should work without a custom ROM