Good morning @hayhayastan,
your husband can obtain a driving license, the actual residence status is no obstacle.
He has to pass the complete theoretical and the practical driving examination in Germany. But he doesn't need to visit a driving school, he can decide himself, if he feels skilled enough to do the tests.
You have to apply for a driving license at your local road traffic licensing department primarily, that's where his Armenian driving license can be acknowledged.
Learning resources for getting prepared to pass the driving license exam in Germany can be bought for several languages (****://tinyurl.***/yc6tdvaq).
Hopefully you have German friends, who can help you in mannaging the issue. More information about driving license can be found at 'Profugus.de': ****://tinyurl.***/y8l4sff4 (German language).