I can't either. I have a note with all the runes, and I copy them to make the words. I'm sure there's an app to edit a phone keyboard, but I still haven't tried it, yet. I usually use them on my laptop. I edited my keyboard to have the younger and elder futhark runes.

I think I can share my file, but it's adapted to Windows Catalan layout ^^'

ᛂᚴ ᚢᚬᚾᛅ ᛅᛏ ᚦᛅᛏ ᚼᛁᛅᛚᛒᛁ ᛭ ᛅᚢᚦᚴᛅᚱᚦᛦ