Just sharing an update here in case it helps anyone in a similar situation. Although I couldn’t find a way to integrate Reolink directly with SmartThings, I had already connected Reolink to Google Home (which I previously mentioned).
Initially, I tested a routine (on Google Home) to turn on the TV when the Reolink doorbell was pressed. At first, there was a significant delay before the TV would power on.
However, without any changes on my end, the routine now works instantly - when the doorbell is pressed, the TV turns on right away and sets the source to HDMI 1 (in the case someone previously turned it off and left it on a different source). I’ve tested this consistently over the last three days, and it’s been immediate every time.
So, if anyone else is in a similar position, linking Reolink via Google Home could be a good alternative. (For reference, my Samsung TV is connected to Google Home through SmartThings.)