I upgraded the battery in my Framework 13 laptop while I was upgrading the motherboard. The original battery still has 80% to 85% of the original capacity if not more (approximately 2.5 years old). It has a straightforward connector on the battery (I think it’s 4S1P lithium ion, appears to use BMS from the motherboard, no onboard BMS). If you have a use for it in a project it’s free for the taking. I can drop it off at the space in my box if anyone wants it.
Here’s the listing for the exact battery. It’s the 55 watt hour version.