Can I connect to devices on the same LAN with a global IP?

In this environment, I understand that you want to access from A to B using the address on the outside of the router.

First of all, it is (usually) possible to access device B from the Internet side by configuring the router settings that are called "port forwarding" or "port opening."

It is up to the router's equipment specification whether it can connect to each other in the LAN, i.e., equipment A, to the global IP address, be successfully address-translated, and actually communicate with B.You should check with the manufacturer's support.This form of communication that you want to NAT with such a return communication is commonly referred to as hairpin NAT.

I don't know if it suits my needs because it doesn't say exactly what I want to do, but could you clear it by name resolution instead of NAT?

If you register the global IP address for outward facing DNS and write the local IP address for inward facing DNS or hosts for Equipment A, you will be able to connect with the same host name from the Internet and from within.I think this method is more common for hostname-based communication.

As I passed by, Sumimasen.
This is called "hairpin NAT"
Are you asking me if I want to make it happen?
above if If you search by keyword, you will find a lot of information
I think I can get it.
Availability depends on equipment specifications and settings.