I know there are some open source Mac apps sold for a couple bucks but you can also build for yourself.
That said, I assumed it’s fairly well-trodden mostly because FSF for as long as I can remember approved/recommended something along the lines of selling builds but completely opening the source. I guess RHEL arguably falls into the camp as well, but they sell more than builds.
I believe the FSF points about selling software come from a time where you sold the medium (like floppy disks) with the software: you had to allow doing this because it was not practical to spread software without doing this and not costing (too much) to the author.
I don't really think it's practical advice for the present, they were never really business model specialists.
That said, I assumed it’s fairly well-trodden mostly because FSF for as long as I can remember approved/recommended something along the lines of selling builds but completely opening the source. I guess RHEL arguably falls into the camp as well, but they sell more than builds.