Petittrack:
https://www.qsl.net/n1vtn/petittrack.html
light and useful, not too tough to add in auto-gps grab to this, I think it is QPE so old QT but is nice and lightweight.
I used Petittrack with a ham radio walkie-talkie a portable cross-band yaggi antenna and a Sharp Zaurus linux PDA running this for years to play with ham radio satellites when backpacking in the mountains.
(edit)
Failing that a current project is Gpredict
http://gpredict.oz9aec.net/
but it is not optimized for a small display, I currently have a whole very old Debian install to rarely run this app.
Gpredict though is not as easy to use mobile.
Petittrack has easy doppler off-frequency tuning for LEO sat passes, and has sun/moon as easy aiming references for back when we didn't have a ubiquitous hall-sensor(compass) in our devices; yea, N900 too.
Petittrack was no bloat perfect for it's target device limitations(no GPS, no Hall) easy clear fast-pass satellite tracking and manual doppler tuning calculation for ultra-mobile LEO communications satellite users.