Hello, I cannot add URLs (due to low lvl acc), but if you write Rise of Bulgaria mod (in Moddb), you will find it easily.

This mod adds the Bulgarian Empire, Volga Bulgaria and 1-2 more nations to the base Stainless Steel mod.

It also changes a ton of other things and is amazing, if installed correctly.

If someone can make the units and flags of the new nations Custom and not generic, would be great, as all other changes
are perfect for veteran players.

I post this here, in case someone can fix the visuals for this amazing mod, since the creator didn't bother with those.