Signage TVs are good for this. They’re designed to run 24/7 in store windows displaying advertisements or animated menus, so they’re a bit pricey, and don’t expect any fancy features like HDR, but they’ve got no smarts whatsoever. What they do have is a slot you can shove your own smart gadget into with a connector that breaks oug power, HDMI etc. which someone has made a Raspberry Pi Compute Module carrier board for, so if you’re into, say, Jellyfin, you can make it smart completely under your own control with e.g. libreELEC. Here’s a video from Jeff Geerling going into more detail: https://youtu.be/-epPf7D8oMk

Alternatively, if you want HDR and high refresh rates, you’re okay with a smallish TV, and you’re really willing to splash out, ASUS ROG makes 48" 4K 10-bit gaming monitors for around $1700 US. HDMI is HDMI, you can plug whatever you want into there.