Great game! I found a bug. You can bypass fighting bosses if you dash outside the door before it closes; you can then collect the powerup without having to fight.
This works on the 2nd (I think) boss where you're dropped from the ceiling. You can hold left, then when at bottom run and dash out the door without fighting.
There are a few other ways I've found to glitch the dash function as well but nothing I can consistently repeat.
Thank you for supporting Linux!
P.S. - This glitch doesn't always work but if you time it right, it does. You hit the floor, jump left then walk left and dash and get past the door before it closes.