If you already did base your list on bootstrappedness, consider this post strong agreement: because that's what I'm trying to say. Yes, there are companies that can be considered "true to the idea of open source" (sqlite! Even though technically neither a company nor open source), but there's a clear cutoff.
I agree with this, though excluding companies burning investors money is already raising the bar higher than for closed source ones. Most companies are not bootstrapped and never leave the pretend zone. Of course not a fan.
XWiki and Nextcloud [1] are definitely bootstrapped. Element is definitely not.
Automattic (behind WordPress) has raised funds, also bought back private stock [3], not clear what it means. They also seem to make money from closed source software.
I would expect any of these company, except maybe Element, to actually make money from their open source activity.
When I'm making those lists, I also don't consider open core and/or obviously VC-founded companies, like Mattermost and GitLab.
Side question, in which ways SQLite is not open source for you? It seems pretty much open source, I'm fine with open source software not accepting outside contributions. They still guarantee the important user freedoms of free software.
[1] https://nextcloud.com/about/
[2] https://www.igalia.com/about/history
[3] https://en.wikipedia.org/wiki/Automattic
> Fully employee-funded and pursuing an organic-growth strategy, Nextcloud already turned profitable by the end of 2016
What do you think about WordPress, XWiki, Nextcloud, Passbolt, Univention, LinPhone, Element, Igalia for instance?
I don't know the internals of each of these, but I believe they all manage to make money from open source by keeping the free software / open source spirit.