The RM mobile app is very old (2015), read only and requires work arounds to give it your RM8 file (dropbox; finder; RM7 export format).
Ancestry has a free mobile app that is continuously updated and lets you work on your website tree. If you have a fast ISP to overcome RM8’s timeout bugs and can upload your tree to Ancestry you have a decent mobile file viewer with hints, search features, etc.