idk, using roam on mobile has always been just fine.
first you open roam on chrome/similar & save the SPA to the desktop as an app shortcut (at least on android)
thus no need to open the brower, no need for the url bar, etc., its becomes like an app.
and then instead of the default simplified version of roam for mobile, you click some button like "full app" or smthn similar, and then it has shortcuts to do common things: