IIRC, when they were first in the news, I believe they were running some insane thing built on top of WordPress (or some other blogging platform like that). At least that was according to someone who had claimed to hack them and scraped all their user data. I think the site was a rush job meant to capitalize on particular dissatisfactions with Twitter.
I believe gab (not so much MAGA as explicit neonazis) is a Mastodon instance, and that's caused trouble for Mastodon clients on various app stores (i.e. if you can use the generic client to connect to gab, the app could fail the app store's content policies and not get approved).