upon reading a bit how different wallets work, it seems macos is able to identify the program requesting the keychain access when it's signed with a certificate - idk if that's the case for signal desktop on mac, and I don't know what happens if the program is not signed.

As for gnome-keyring, they ackowledge that doing it on Linux distros this is a much larger endeavor due to the attack surface:

An active attack is where the attacker can change something in your security context. In the context of gnome-keyring an active attacker would have access to your user session in some way. An active attacker might install an application on your computer, display a window, listen into the X events going to another window, read through your memory, snoop on you from a root account etc.

While it'd be nice for gnome-keyring to someday be hardened against active attacks originating from the user's session, the reality is that the free software "desktop" today just isn't architected with those things in mind. We need completion and integration things like the following. Kudos to the great folks working on parts of this stuff:

- Trusted X (for prompting)
- Pervasive use of security contexts for different apps (SELinux, AppArmor)
- Application signing (for ACLs) 

We're not against the goal of protecting against active attacks, but without hardening of the desktop in general, such efforts amount to security theater.

Also

An example of security theater is giving the illusion that somehow one application running in a security context (such as your user session) can keep information from another application running in the same security context.

In other words, the problem is beyond the scope of gnome-keyring. Maybe now with diffusion of Wayland and more sandboxing options reducing this context becomes viable.