It's more natural to play the Réti Gambit 2. c4!
Potato Gambit - New Opening?

It's more natural to play the Réti Gambit 2. c4!
The idea behind a4 (from my speculation) is that it helps take queenside space and after 7...Qd4?! the best move is 8.a5! which stops the move 8...h6 (which is losing after 9.a6!!) if black plays 8...Rc8, the best move, then white still plays 9.a6 and the only move for black is 9...b6 (if 9...bxa6 then 10.Rxc6!)
So I found out about the existence of the potato opening (1. Nf3 d5 2. a4) a while ago, and recently decided to look into it a bit before stumbling upon the interesting idea of giving up the e-pawn and then developing rather quickly.