I mean, you
can take your iPad back to Apple and have them replace the battery, you know. For my current one (a "4th generation" Air) that'd be $120, which is not cheap, but it's cheaper than replacing it for $700 and a lot less stressful than trying to replace the battery myself.
(Having said that, I'm not ruling out replacing it, but I don't think I'll be inclined to do that until they stop updating its version of iPadOS.)