I use Lets encypt and OVH DNS for my certs, I can get a wildcard for mulit service nginx or a single cert for the places that need them.
The other thing I want to look at is the Small Step CA, I use that for SSH certs
They only killed the old tach off cuz the masses moved in, in the early days (think dialup) you had only the tech savvy online. You had to wait for everything, email, blogs, news the lot.
Then the alway on internet landed and all that stopped, now you can reach anyone anywhere. all the non-tech savvy joined and the mega corps saw the rich gold mine.
The real issue is the lack of tech savvy people making small sites, the mega corps have the platforms and thats where everyone went. Its cheap and easy to be on a mega platform then to run your own site, anyone who does run a site will not see much traffic as its hidden by the big names
The way I sorted it was to run nextcloud for a week, then run ps aux on the host and see what the memory use of a php process is.
The 5th column is the memory use of a process, divide the number into the amount of memory you want PHP to use. The number from ps is bytes, so you will need to use some maths to make it all fit
in Debian running PHP-FPM in /etc/php/{{ php_version }}/fpm/pool.d/www.conf
edit or add the below lines with the settings you need
I run Nextcloud, its responsive and has all my stuff in it. Notes, Calendar, Contacts, Kanboard, Photos, RSS reader, others.
You do need look at the setup, how many PHP processes are you running, how much memory does MySQL use.
My current setup is a a PHP vm, 6 cores and 8GB of memory and a MySQL vm that is 2 cores and 8GB memory. But I work for a SaaS provider and thats now we carve up our systems, a vm/instance for 1 job.
Without knowing why you need a local GitHub like tool is almost impossible to suggest, but I know Gogo's can keep a remote in sync if you need. Also there is a python tool to backup your GitHub account and or organisation
I run Debian on all my vms, they have no GUI installed at all. I manage all of them over SSH