I just got this working! Noticed that it was hanging on the splash while trying to set up some sort of wifi networks, which android isn’t allowed to do. So I tried denying the permission for that, and now it starts.
Open the Android settings app by tapping ‘Android version’ on the AppSupport settings page. Then go to ‘Apps and Notifications’ > Advanced > Special App Access > Wifi Control and set Roborock to not allowed. I don’t think you’ll be able to set up a new vacuum on Sailfish as I think that’s what the wifi thing is used for. But if the thing is already on your wifi network then you should be fine.