My 2c - I've not read all 18 pages of this thread, but I've seen my use-case and circumstances listed by others - I use a Mac, not because I want to any more, but because I can't get things like Affinity Photo on Linux (I'd probably opt for something Debian based). If I could buy Affinity Photo for Linux, I'd do so, even though I've already paid for it and Designer on the Mac.
£50 - £100 for a licence is not going to be a barrier for me. I can get away with Linux office products or even use MS 365 via a browser, but I can't deal with no decent graphics software, and Affinity products do just what I need. So, I think that if word gets round that you can buy this for Linux, you may lose some Mac licence sales, but you'll lose them to people buying it for Linux. And you may get some people like me who will happily pay you twice...