That is one of the advantages of the bigger name brands, replacement parts are generally a lot easier to find.
They don't manufacture batteries and never have, I've always had mixed feelings when it comes to "supporting their goals".
I appreciate their work to get Linux working on those models, but they can't provide long term hardware support.
https://www.dell.com/en-us/shop/dell-97-wh-6-cell-lithium-io...