Regarding moves on the A-axis it should work using Gcode, but there is no support for displaying the coordinates or visualising yet. That is a current work in progress: https://github.com/winder/Universal-G-Code-Sender/issues/1068
The TinyG/g2core support is quite new and I haven’t had the chance to test it with a TinyG boards yet. I’ve been developing on a g2core board which seems to work: https://github.com/winder/Universal-G-Code-Sender/issues/1071
Regarding transferring files, this is outside the scope of UGS and a bit dependant on your setup. Maybe a USB-stick or SFTP?
