Ad 1: You’d have to try it yourself, but to me, Obsidian works flawlessly on Mac. As another commeter said, it has a certain VS Code feel to it. No iOS app yet, but I think it’ll come sooner or later — you should keep an eye out.
2nd: Obsidian can transclude whole files or whole sections (afaik). No block-level transclusion, as there isn’t any concept of blocks in Markdown, but that shouldn’t matter much.
I’m curious what do you use block transclusion for? When I used Roam, I did occasionally have a need to link to only a small part of some note, but that happened so rarely that I happily traded that in for the Obsidian-specific features (md based, offline-first).
Most serious writing I do will consist of remixing the same ideas over and over again until it its practically unrecognisable. Roam is the perfect tool for making a collage of text while also keeping a reference to the primary sources.
A simple search on youtube will show you how people use block references btw.
2nd: Obsidian can transclude whole files or whole sections (afaik). No block-level transclusion, as there isn’t any concept of blocks in Markdown, but that shouldn’t matter much.