YOu can get a month of g6, but really, i think dexcom g6 or 7 is overkill. Possible dexcom one, but i think you do need to commit for 3 months there.
Libre is accurate enough, especially if you are not on meds that cause hypos. I was on it for about a year and it was ok, but it would wake me up with false lows...not an issue if you are not on hypo causing meds as you can turn the alarns of.
You can get around the limited phones with the 'build your own dexcom' app you can get fre
On reddit, but if i were you i'd go for libre or fingerpricking and save your money for fresh, natural, healthy food. End of day, its diet and excercise that will bring those blood sugars down, and monitors etc just give you an idea if what works