ECG

Hi

you are right according to https://www.apple.com/watchos/feature-availability/#branded-walkie-talkie it is available. However availability is determined by the country the watch was originally sold in. This watch may of being imported from a country that is not support like china

Also make sure you do not VPN on, and have not chosen a different region in settings

If you did buy it directly in Bulgaria from apple, reach out to Apple support for further guidance

go ahead and make a backup and update the iPhone

it does not matter if they were bought in Bulgaria or not, it means you have to but them from apple in Bulgaria as some random store in Bulgaria could just be importing a cheaper model

Were the watch and phone both bought in Bulgaria?

Is your phone updated to ios14.7.1?

Is your watch updated to WatchOS7.6.1?

You need to update the phone.