Best of the solutions I tried (steam link for quest, ALVR, oculus link)

Yes, works best of the solutions I’ve tried

I got rid of the Q2 a couple months ago but never had issues.

I used Virtual Desktop, not SteamLink

You don’t see a lot of issues because the few people who ever used SteamVR on Linux ran away screaming and never came back¹

¹I made that up, but it’s bad

“limitations” - I couldn’t auto-update apps or the OS, I considered that a feature. I didn’t do anything besides use VR Desktop and try and fail to use ALVR, that all worked fine. ALVR didn’t work because SteamVR on Linux is hot garbage, not because of my DNS blocking.

I did this by getting rid of my OQ2, but until then, I used this list in my DNS adblocker, which seemed effective:

0.0.0.0 oculus.com
0.0.0.0 oculuscdn.com 
0.0.0.0 facebook-hardware.com 
0.0.0.0 graph.oculus.com
0.0.0.0 fbsbx.com 
0.0.0.0 crashlytics.com
0.0.0.0 edge-mqtt.facebook.com
0.0.0.0 scontent-frt3-1.xx.fbcdn.net
0.0.0.0 rupload.facebook.com
0.0.0.0 graph.oculus.com
0.0.0.0 graph.oculus.com.lan
0.0.0.0 mqtt-mini.facebook.com

Are you responding literally “stop” or are you editorializing like “please stop for the love of Satan”? The former is supposed to be seen by the system and you’re supposed yo be automatically unsubscribed. The latter goes to a person and that person may try to engage you. At least, when I’ve done text-banking, that’s how it worked. A less reputable system may try to engage you regardless. If you get sent to a person it’s also up to the person to decide if and how they talk to you. If I saw something that made it clear the person didn’t want to talk, I would tell the system to unsub them, others might try to be persistent.