It doesn't sound like you need to use the mobile app at all. Why not just put links to the dashboards on your phone? I know on Android you can save a URL from the browser as an icon on the phone. I assume iOS can do the same.
You can also use the "Link" tile on a dashboard to link to any URL, including the dashboard on your other hub. So you can quickly jump between dashboards on the two hubs by putting tiles on each that link to the other one.
The app has never been a huge priority. Even when it was introduced it was really just a basic effort to quiet the clamor for "an app", but in reality it's not much more than a web wrapper. I haven't used it in a couple years . The only thing I was using it for was Zwave Smart Start,but even that doesn't seem to work anymore. I recently tried to use it to add 6 devices. I ended up having to add them all the old way, as Smart start never did anything.
it is not only for "paying customers" it works in the same basic manner regardless. it just isn't a particularly useful app in general. The native dashboard really isn't much better. There are third party integrations that are much better and much more aesthetically pleasing. For Android I highly recommend you take a look at HD+ or Sharptools. You can even set sharptools to be the default dashboard in the Hubitat app. For notifications, your just a well off to pay the $5 for a Pushover licence and use that for your notifications.
Quite. Amazing bit of kit.
Sharptools has been around for like 10 years, fyi.
precurser to sharptools... smarttiles .. have rights to use the source locally (not distribute) back from the smartthings days
SmartTiles was the precursor to ActionTiles (not Sharptools).
I put links on all my dashboards that "link" to my other dashboards (using the NON-local links, so they work remotely).
If you want to easily bop over to a dashboard on your other hub, you can easily do that by putting a link to it on the opposite hub's dashboard, and vice versa.
Then, consider putting the non-local URL for one of them on your phone's home screen.
One click and you're on the first dashboard. One more and you're on the other hub's dashboard.
Tweak the colors and other things on the dashboard (via CSS) if you want to change the look a bit more than the standard options allow. You might need to find an html nerd for some help on that 
Download the Hubitat app
