I'd love to hear from someone that works at GitLab on how things work internally. My understanding is that they have hundreds of employees and are 100% remote. Seems amazing from my outsider's perspective.
We are all-remote with hundreds of employees as you noted.
You can read more about how things work at GitLab via our handbook and our all-remote guide:
Unknown companies doing remotes will pay more if you're decent at negotiating and selling yourself.
Buffer has better salaries, I may explore that at the next switch.