@danielchsny from your tlp command output, linux cannot see the battery because the computer cannot see the battery. tlp pulls the data from the ACPI which is "Advance Configuration and Power Interface" and since the computer doesn’t see it, the operating system doesn’t either.
It is possible to get a better understanding of the problem by following @danj ‘s recommendation of running the AHT (Apple Hardware Test).
Go to this github https://github.com/upekkha/AppleHardware... and follow the step to installing it. Since you are only installing a diagnostic tool on your Apple hardware, it’s not illegal to do. Go down to the MACBOOK section and select the MACBOOK2,1. This is the earliest version of the test (I’m not sure the macbook1,1 came with the test, @danj would know better).
Instructions are further down the page so read it all before proceeding. This will give you Apple specific feedback on Apple specific hardware and @danj can help you further (possibly).