Anyway, beefy HP laptop with 32gb ram and Xeon CPU to run all services. 3 RAID-1 (Linux sw raid) usb3 volumes to host all services and data.
Two isp's: Vodafone FVA 5G (data capped) for general navigation and Fastweb FTTC (low speed but uncapped) for backup access and torrent/Usenet downloads.
Gentoo Linux all the way and podman, but as much limited as possible: only immich (that's impossible to host on bare metal due to devs questionable choices).
Services: WebDAV/webcal/etc wiki, more stuff, arrs, immich, podfetch, and a few more.
Not saying it's not secure, just that I'd have constant doubts whether I've covered all the bases if I were doing it. Especially ensuring an intruder can't compromise anything else if they take it over via some security exploit in PHP or DocuWiki itself.
The service runs as an unpriviledged user, even if, at worst, an intruder would delete or replace the wiki itself. Even the php-fpm behind it runs as that unpriviledged user and is not shared with any other service.
I doubt an attacker could do anything worse than DoS on the wiki itself.