@ahmi I am a fellow user, and I can possibly shed more light from a user’s perspective on your issue: I started using Seatable as a private person, hosted on my own VPS, and brought it into my workplace, to be currently introduced in an organization with 17.000+ employees.
IMHO, I suspect that your definition of “beginner-friendly“ is not mine, even when I started as a private person. If you mean “foolproof“ or “saves work to research / learn the basics of running such a system“, I would not follow. However, it is totally manageable for a developer like yourself to run a self-hosted Seatable installation - if you are willing to learn the basics.
I wouldn’t hold it against Seatable that they don’t see it as their duty to spoon-feed you the basics - most of your list is generic. If Seatable compiled such a guide, it would just copy information that has been given elsewhere. To be precise:
Any Linux that can run Docker - that’s the beauty of a containerized application. The exact Linux distro has a lot to do with its maintenance. Which can only be judged with generic knowledge and individual experience and preference.
- Minimum VPS specs for real-world usage
Depends on the size of your installation. My private VPS has 4 Cores, 8GB RAM, 120GB SSD, and runs my 3-user free installation without problems. Costs 6,99€/month.
- Full Docker + Docker Compose setup (from zero)
Sorry, certainly not something for Seatable to write about. A link to Install | Docker Docs is all that is needed. And there is basic information at SeaTable Server - SeaTable Admin Manual .
The same. Especially since it’s highly dependent on your Linux and Hoster choice. But since Seatable supports Caddy in its standard install, you are probably best advised to rely on HTTPS quick-start — Caddy Documentation . There is even a step-by-step guide 
- API usage confirmation (same as cloud)
@bha just confirmed that
You will be suprised what you find on https://forum.seatable.com/
To summarize: You need to learn your generic Linux, VPS Hosting, Caddy, HTTPS/Domain, Firewall(!), Networking, Docker and Docker Compose skills elsewhere. Seatable is very generic regarding the underlying basic techniques, so no need to re-invent the wheel.
Equipped with these skills, you will literally be able to install Seatable in 10 Minutes like SeaTable Server - SeaTable Admin Manual says.