A lot of the responses to your comment imo are kinda missing your point. I don't use Apple products, but I do understand what you're saying. You want an editor that also has an option for previewing the markup text in its formatted view.

It's officially only available for Linux (the Windows version is currently under development), and like I said, I don't use Apple products, and idk how familiar you are with manually compiling source code or how good Wine is on Macs, but maybe [Remarkable](https://remarkableapp.github.io/) could be an option?

Just thought I'd give my $2.70. ;)