I don't use them, but that is surprising! I would program one of my theoretical phone's physical side buttons to handle PgDn/PgUp [†] – similar to my old Kindle's layout. Do phones still have side volume buttons (e.g.)?
[†] Thanks for the better styling, than my former Page_Up &c
Or what I actually use for ssh on the road: https://github.com/klausw/hackerskeyboard
Google kicked it from their store because it still supports older Androids but it still works just fine on the latest versions. It's on F-Droid.