Take good note of oldfred's advice re UEFI etc. It's REALLY important advice.
If there's no Windows then don't sweat it, you can do any shrinking with GParted.
IF, at some point, you do need to shrink a windows partition use the Windows disk management tool (start > computer > manage > disk management) to avoid corruption & ruining Windows.
Other than that, you've understood my thought process accurately.
It does look like you aren't going to need Windows though, which is nice
(I keep Windows around to use as a big video game machine).