

We kind of selfhost almost everything - while we operate a small server ourselves, the main burden is on a dedicated server setup. Basically a FreeIPA+Authentik+OpenCloud Stack as a base,with Redmine, Kimai, Zammad, Matrix, Jitsi and a few more apps. (Moodle, Seed DMS, Netbox, Zabbix, OPNsense, Vaultwarden, Forgejo, Ansible). Additionally we use a fair share of software remotely via RDP.
Backups are done onsite and to three different offsites, including cold storage backups.
As we all work fully remote this setup is also fairly adaptable and the switch to a (almost fully) Linux shop went far better than expected - my staff is fairly content with their setup (afaik).
The only thing I refuse to selfhost are email and VoIP.

Xwiki is missing.
For me after a similar search it is the current winner. Even though it has it’d downsides. We came from Confluence and tested a LOT of systems. My spreadsheet of systems we considered has around 120 rows by now. (Not all pure wikis as we also moved away from jira and considered going down a “put the wiki into the servicedesk” route)
Pro:
It is well tested in a enterprise enviromentand mighty
It has all the features I personally found important for a company wiki, e.g. approval, versioning, templates, collaboration, integration api,etc.
It is fairly easy to extend it yourself
It is easy to host subwikis within the same installation with a self defined grade of independence - which is great for customer facing things,large projects with externals,etc.
The development community is big and enterprise focus and release cycles are good. (Not like a certain .js) There is very little chance it will stall suddenly as the wiki has been adopted by a lot of large companies which seem to support it.
It’s truely free,no “pay to get custom fields” bullshit.
It’s truely self hosted.
it can be hosted system side, if you are not into docker.
Contra:
It is written in bloody Java
(even though this sentence is redundant with the one above) It is a resource hog
The look and feel is a bit outdated unless you customise it yourself. Then it is reasonably good.But there are basically no paid templates,etc.
Paid support is only available through third parties it seems.
It can be, well, slow to update…like physically slow. It is not hard to update,not at all…press a few buttons…but sometimes it takes ages.