During the 1920’s, Walther sold a toggle-locked semi automatic shotgun design. However, it was unsuccessful due to the severe recoil it had. A weapon like this would make a great candidate for a gold order weapon for Germany, it would be extremely fun to use, unique to the faction, and not significantly alter the current meta.
It would obviously perform worse than the Browning Auto 5, with only 4 rounds and worse handling, so the USA would still be king of the shotguns, do not worry!
Here is more information about this unique weapon
Of course, I’m sure the Soviet Union and Japan would enjoy gold order shotguns too. I may make another suggestion thread for these ideas too if others think it is interesting enough.