I understand what you're asking.
Basically, you want to create a virtual channel with stream links.
I could be wrong but I'm pretty sure Channels DVR doesn't support this.
My understanding is this: in order to create a virtual channel, Channels DVR needs to know how long each item on the channel lasts so that it can generate an EPG for it.
Stream links don't contain the information of duration for each movie/episode.
Technically, I guess you could create an EPG, but the devs would still need to add support for this in the software to open the streaming app at a specific time.
Besides, once the streaming app (i.e. HBO Max) is open, whatever happens in it is unknown to Channels. It can't play and stop anything in it.