• XMPP
• Signal
• SMS (contacts only)
• E-Mail (only a handful of important contacts, forwarded to an inbox specifically for my phone)
• Voice calls automatically dismissed with a missed call notification. Colleagues, friends, and family are aware that I'll initiate the return call.
• Task reminders at one point, but later switched to paper planners.

Total: about 5 to 20 on any given day

Haven't ever felt the need to get YT or other subscriber notifications and one of the first things I do when setting up a new browser is disabling all requests for notification permissions.