Check out this description: Question about ReSound app.
Since posting, ReSound has published an update to the app, and I’ve been looking at the app more closely. The in-app documentation seems to say the default is a single volume slider. If that actually were the default on my phone, I think I’d be happy.
Meanwhile, I emailed app support. The email apparently went to Denmark, and they’ve redirected it to North America. That doesn’t delight me, but I understand it. I’m not expecting an immediate fix - they need to figure out if it’s their problem or mine, code and test a fix, etc. I offered to test the fix, and I hope they take me up on it.
I still haven’t tried the app on my wife’s Mini SE(2020).
This is a significant annoyance, but I like the Jabras enough that I’ll go Apple if that’s the only way to solve it. Going Apple, after years of disliking them, is a big compromise for me. 