m1 battery degrading

I have an m1 MBA, it's 6 months old and has 70 cycles on the battery. It's down to 88% design capacity. Is there anything I can do? I'd be willing to even pay out of pocket to have the battery replaced but the issue is that the local "Genius Bar" said itll take 5-7 business days to have the battery replaced... 1st, thats BS, unless they are manufacturing the battery from bare chemicals it should never take that long. 2nd I use this machine for work and I can't be without it for a calendar week and a half. Is there anyway to back build the Mac charge capacity? Or somewhere I can buy a new OEM battery? Im not afraid to install it myself. Tbh if i have to be without it for potentially 10 calendar days I might as well buy a new one, I'll be out less money.