Losing to 1. a4

On a scale of 1-10, how bad is losing to 1.a4 2.h4?

seems similar to pawn odds, so maybe he weakens himself by ~100 elo or so by doing that. The effects of handicaps on rating is an interesting subject, if you want to research that.

Its worse then playing 1.a4 so its pretty bad. Anyway, if some person who is higher rated then you plays it, its not that bad.Its worse to loose being queen up then to a4,h6,nh3 etc.

It all depends on strengths..... Someone who is very strong can play from inferior positions and win, vs people of lesser strength..

No one answered numerically yet so I'll say ... 5.

To me the opening is both extremely important, and not so important.

Hope that makes sense... If you play Carlsen, he might play 8 Knight moves before beginning to play, I've seen him do that.

Or a little more common, switching Queen and King by c3, Qa4, Qh4, f3 etc.

On the other hand, 1.a3 is not really a bad move at all, and with 2.c4, Nc3, e3 etc can turn into a good game.

1 a4 and 1 h4 are not bad and probably just lead to a drawn position with best play from both sides and thus are objectively no worse than 1 e4 or 1 d4.
Openings are overrated.
Play the white side of 1 e4 f5, 1 e4 b5, or 1 d4 g5 against Stockfish if you doubt that.

To start, your opponent is basically giving you the advantage of white plus an extra tempi. It becomes less of an advantage if you end up transposing to a position where a4 and/or h4 makes sense.

a lot less worse than Trent losing 4/9 games to Magnus with rook odds :))