I definitely recommend picking up trade paperbacks instead of individual issues if you don't want to worry about continuity. They usually all have what you're looking for: a self contained story line where you just need to know the basics of the character.
I highly recommend the various Spider-verse storylines, personally.
Also many issues and trades will have narrator boxes explaining the gist of what you need to know to have context from past issues you may not have read, almost always citing the exact issue if you're curious (obviously that probably helps with sales too).
The Nick Spencer run of Spider-Man was excellent, IMO, and has some amazing art to accompany it with some absolutely top notch two page spreads to boot.
Since I see no replies yet, I'll give a sort of answer. I use Overseerr and my own self hosted domain name with Cloudns so that I can let my friends/family connect to it remotely to request stuff.
It sounds like it's definitely not 1:1 with what you're asking for since it only does sonarr and radarr and is not something accessible from messengers, but figured I'd mention it because it's been great for me. I use it for myself to add new stuff as well so I never have to go into the individual sonarr/radarr instances to add stuff.