I've never tried to self-host something like that, but on the other hand, I've never worked at a place where the internal GitLab wasn't a shaky mess, particular

I've never tried to self-host something like that, but on the other hand, I've never worked at a place where the internal GitLab wasn't a shaky mess, particularly when CI or Pages or certificates is involved. I believe people when they tell me they've managed it without major problems, but clearly they're the 10x developers of the self-hosted world, because the people I work with seem to find it hard - and that is not a slight on them, because clearly even Github can't do so much better!