Can you tell me about 1.a3-b4?

Basically, 1. a3-b4 leads to a very forced sequence, and it may be too sharp for lower intermediate players and beginners.

After 1. a3-b4 b6-a5 white can equalize (and there is a difference between Russian and Brazilian variants: as far as I know, 2. g3-h4 is the best option for Brazilian, while 2. e3-d4 is the most active response in Russian), but black is the dominant side for dozen moves.

There is an example in youtube which shows how this opening can turn bad for white:
youtu.be/DODYv0jOeB4?si=BcHCRs2wyUNCBgYJ

12

Thanks