Yes, it works well but there is a limit of 16k words. See this reddit comment thread [0] for more details, but if your documents are anywhere near that big then I'd say Postgres is definitely not the right tool for you.
I often see complicated search solutions implemented when PostgreSQL is just sitting there with its incredible FTS powers being ignored. To help some of the teams I'm working with get an idea of the power available to them I wrote up this two part article with a github repo for spinning up a db to follow along.
The interface is a bit clunky (when the diagram text is invalid, you see markup) but it makes it easy to create diagrams that are embeddable in Google docs without reaching for google draw.
I don't know about the others, but Azure DevOps' mermaid support is several releases out of date, or custom-limited to certain features. This means a lot of the examples in the official docs or elsewhere online don't work.
But what is most frustrating is that they don't document what features or version of mermaid they actually support. Microsoft gives a couple examples with links to official Mermaid docs, with a huge vague warning that _some_ things won't work in DevOps.
I know LinkedIn is bad but a link to Twitter that links to LinkedIn is worse.