Some of the most popular and best aftermarket GLOCK magazines are made by: ETS, Magpul, ProMag, KCI, Amend2, SGM Tactical, Shield Arms, Advantage Arms, and FAB Defense.
The G44 use a simple blow-back mechanism similar to the G25 and G28. I received a G44 sample prior to the January 2020 release and have started to run it.
The Timberwolf frame changes the girth and grip angle of a G20 and G21. Those of us with average size hands or smaller find the standard G20/G21 grip a bit fat...