What's best for zons in pvp? Those charms or something totally different?

Yes.

3/20/3 until you want to reach whatever number. then 3/20/20.

mostly 3/xx/20s if you can afford it. 30 frw circ, eni, 30/40 frw boots and possibly cats eye will give you enough frw

while 3/3/xx aren't exactly cheap they are still a great budget/cost efficient alternative

5@ 3 frw until you hit max resist
3 frw 3 Max xx ar until you hit desired frw breakpoint (from memory 125 135 and 150 are reasonable spots, Google “frw table”
Rest 3/22

You want at least 150 frw with shield/titans out. I usually do 25 frw charms, the rest 32020s.