My guess is it wouldn’t work. On a magnetic antenna, the number of turns don’t affect range, but they do affect the frequency to which the antenna is tuned. It needs to be tuned roughly to the frequency the protocol operates on, otherwise it won’t work. In addition to that, these antennas also need to pick up power, which is also relative to the number of turns.

For /e/os: basically like android. For postmarketos: similarly to how desktop apps are developed - you use a programming language of your choice, and a GUI toolkit. Popular toolkits are QT (used by KDE) and GTK (used by Gnome). Whichever you choose depends on taste - apps written using either should integrate reasonably well with all mobile shells in postmarketos, but of course GTK apps will feel more “native” in a GTK based shell (and the same for QT and KDE)