Hi Teemu, I tried the flatpak version of puremaps on my device and then turn-to-turn navigation worked pretty well, I think for navigation on mobile phone it's a better option than organicmaps, and I'd like to see it landing in Debian. Based on your work I've made some progress and have a usable package for it, once it's in a more polished shape I will push it to salsa :)
I saw the salsa repo[1] you worked on, are you still interested in maintaining it? Perhaps we can co-maintain it? https://salsa.debian.org/DebianOnMobile-team/puremaps/puremaps

