Have you looked at Obsidian URIs? It has a vault parameter:

https://help.obsidian.md/Advanced+topics/Using+obsidian+URI

I tried using the URI-scheme and vault-parameter some time ago on linux, to open specific vaults via script. Surprisingly, this did not worked at all. Even worse, the whole scripting of obsidian is horrible even on the fundamental levels, and it failed on pretty much any normal job. Though, this is not such a surprise, considering that it's complete foreign to linux any kind of integration. At the end, it's a closed space, not like an editor, open to the rest of the system.

Thank you. But it does not solve the issue. The custom URI concept is too complex and alien in the Windows world.

A Windows user would much better prefer to have a special anchor file in Obsidian vault folder that could be double-clicked and treated by the standard and observable means.

This is why .txt files are so popular. A double-click and they work. The specialized tools may be 100 times better, but they often miss one important detail: frictionless entry. If something causes friction, especially at the start, then it gradually becomes a burden a user doesn't want to deal with.

However, you advice solves the issue for me because I'm a technical user and you have kindly presented the information. But just imagine how many of those who would totally miss that.

This is a great opportunity for you! This is a problem you know lots of people have and since you are a technical user, you could probably solve this for yourself and others in the same situation. Write a small application and register a file extension for it (maybe .obsidian). When you double click on sql.obsidian (for example), your app would launch read that file then launch Obsidian via the obsidian:\\ protocol.

Your launcher app could also handle the creating of .obsidian files or (even better), write a plugin for obsidian to export a .obsidian file.

you can do that using uris:

https://help.obsidian.md/Advanced+topics/Using+obsidian+URI

there is also a plugin for having advanced uris if you want to be more specific:

https://github.com/Vinzent03/obsidian-advanced-uri

Remember Obsidian is fine with files coming in from outside. You can just write text into its folders, using anything.

Not sure how to do this on Windows any more, but on MacOS the trick is to use a Shortcut that captures your whatever (text input, image, web page converted to Markdown, file) and writes it into the appropriate vault and optional subfolder.

Can also capture to, e.g., Downloads folder, and have a cron move it to the vault. (I do this when capturing web pages so Browser can't write outside Downloads.)

Anything that can capture to a file path, can capture to Obsidian.