The Voron profiles are not very similar to the Prusa MK3s profiles.
The short way is to remove the "Compatible printers condition" restriction to be a prusa....
Set the printer to Prusa MK3s.
Filament to "Generic PETG".
Switch tab to "Filament Settings".
go to sub tab "Dependencies"
Remove Prusa Vender string in compatible printers condition.
The long (but still useful way is)
In PrusaSlicer 2.6 Set Printer to Voron.
Set filament profile to Basic PET.
Open tab for "Filament Settings"
Click on save profile (you need to have a local profile to overwrite)
Click on Prusa Diff (mouse over says "Compare this preset with some other"
Check "Show all presets (including incompatible)"
Change left box to "Generic PETG"
All of the changes will be visible...
On the bottom (in 2.6 only) is a check box "transfer values from left to right"
