This is coming from dogfood feedback in this thread: https://groups.google.com/a/google.com/d/topic/better-together-dev/QErFHBDaf-E/discussion

Specifically, these two points around GmsCore notifications being disabled by the user on the phone side:

"""
1.  The screen of directions for turning on Google Play Services notifications
is incorrect.  It says to go into Settings > Apps & Notifications >
Notifications > App notifications.  There is no such button.  See this photo of this incorrect set of instructions.
	https://photos.app.goo.gl/tsbHAjCn58JbbzZUA
Instead, I had to access it via Settings > Apps & Notifications > See all 157 apps > Google Play Services.  Suggestion: fix the directions. 

2.  Turning on these notifications (which were previously off) will probably lead me to receive tons of notifications I'm not interested in.  I shouldn't need to enable a ton of notifications in order to enable this feature.  I tried disabling it after forming my first connection, but apparently it needs to stay enabled indefinitely.  This seems like a hack.  Suggestion: find a less hacky way to instantly tether, which doesn't require the user to enable notifications
they don't want to see.
"""


Re 1), it looks like things moved around in Q, which is going to cause us some issues here. Besides that, now that we're rolling out to non-Pixel/Nexus devices in January, these instructions will be impossible to always get right :-(. However, I actually think we should solve this with my comment to the next point. 

Re 2) Now that we don't have Android client devices (which can receive mobile data via Magic Tether), I think we should reconsider our decision to totally block tethering if GmsCore notifications are disabled. We may need to talk to privacy/security again to validate that it's ok (the persistent notification was required by those reviews), but I think it's not the end of the world to rely on the standard platform tethering status icon if we can't show the Instant Tethering persistent notification.

The one use case where we'd need to figure out an alternative UX is the first run flow. On first run, we use a notification on the tether host device to start carrier provisioning with visible UI from the carrier. If we can't show a notification during that time, we might need to pop up a new activity (if we can even do that from a non-activity context) or figure out some other way to get into the provisioning flow. Shiba can you take a first stab at some ideas here?