notebook is a 10 year old macbook pro without macos I installed xubuntu 24.04 in. It comes with an embedded battery.
First notebook I bought, not from apple, had a removable battery. The vendor told me to maximize its life I shouldn’t plug the battery in, unless I need it (like for traveling). This way, I’ve managed to keep the original battery in good working condition for 8 years so far.
Back to the macbook: I cannot remove the battery and constantly loading it to up to 80% and discharge it up to 20% seems ridiculous. Furthermore, this would deplete the battery even faster, I believe.
What can I do to spare the battery as much as possible?
It’s a miracle that the battery is still working at ten years. The most realistic thing is to just keep up with your backups, and be ready to dispose of that laptop the moment the battery starts swelling.