Well, if you want private images it is normal that they charge you for it. What I advise you to do is to make the images public and mount the private part as a volume. This way you can upload the images wherever you want without worrying.
Another option if you want the resulting image to have something private is to create as much as you can in a public image and have a script that adds the private part as the last layer.
Apart from the registries you have in GitLab and GitHub if you are looking for something more generic like Docker Hub you have Quay (from RedHat). It works very well and has a pretty nice interface (especially the new one that is in testing).
You don't really need Cloudflare to have your own domain, you can do everything directly with GitHub.
It is not about leading anything but about having the code in a repository so that it is easy to read/consult/audit/etc.
You can upload the code to any service (it doesn't have to be GitHub, it can be GitLab, sourcehut, etc...) and disable issues and comments.
Synching is currently the fastest and lightest you will find, but the concept is different from Seafile or Nextcloud. With Synching there is no central server, you have resources (folders) shared between nodes on a peer-to-peer basis. This has several advantages, the most obvious one is that if a node goes down the rest continues working, but also that if a file is available in two or more nodes when a new node enters it will download that file from all the nodes in which it is available. As a disadvantage we could say that there is no web server where to see the shared files, so you will not be able to enter a URL with username and password and browse the files and upload or download. You will not be able to share files with third parties through a URL either.
Best alternatives:
Self-hosted:
Other alternatives:
About that I have made the simplest possible implementation of a syslog server in Rust. I use it to collect OpenWrt logs and store them on my server. ;-)
restic without any doubt. I use it with S3 backend and SSH copy and it has an excellent performance (with copies of years).
Borg I was using it for a while (to compare) and I do not recommend it, it is not a bad product, but it has a lousy performance compared to restic.
Kopia I didn't know it, but from what I have read about it it seems to be very similar to restic but with some additions to make it pretty (like having ui).
Some people say that Kopia is faster in sending data to the repository (and other people say it's restic), I think that, unless you need ui, I would use restic.
I know this is not the best answer since you would probably like me to talk about Nebula, but I have to say that the best solution I have found for setting up a mesh VPN is Zerotier.
It is a very complete solution. Multisystem, very simple but very configurable, fast, etc.
You simply start by creating a network on the public controller (which will generate an ID for that network) and then join the rest to that network and everyone can communicate with everyone (by default, then you can create subnets if you want).
Using the public controller is completely optional (I personally use it because it is convenient for me and because I have few hosts) but if you want you can set up your own controller, I have an article (the bad thing is that it is in Spanish, but if you run a translator you can understand it perfectly) where I explain how to do it without any requirement. If not, you can use ztncui for it.
Take a look at it, you might find it more attractive than Nebula.
By the way, for me one of the great advantages of ZeroTier is that I don't have to worry about certificates and keys, the controller takes care of everything for you and security is guaranteed from the point of view that each node has a unique identifier.
If you live in Europe you have 1TB by € 3.81 / month with Hetzner. It works fantastic with Restic (I'm using it too for my backups).
I was an Inoreader user too, but I discovered Miniflux and cannot be happier 😉
Or you can directly use Glowing Bear without installing anything.