Sure, I am passionate about Russian grammar too, and I used to correct mistakes of native Russians writing in Russian (I stopped doing that when I learned that dyslexia is quite real and common, and I now feel sorry for that).
However, any foreigner trying to speak Russian, no matter how broken or incorrect, will meet nothing but praise and encouragement from other Russians.
Except the lady who sells subway tickets in Moscow. That lady is quite grumpy.
(Everyone else was kind.)
I took immersive classes, speaking 6 hours / day, 90 minutes spent on pronunciation drills. The only downside is my accent got better faster than my vocab, confusing lots of people with whom I interacted.
However, any foreigner trying to speak Russian, no matter how broken or incorrect, will meet nothing but praise and encouragement from other Russians.