Tried to install the newest (long-awaited) Elementary OS 6 Odin on my old MacBookPro 5.5 13" (from 2009). It was my first Apple Mac, and as of now the only Mac still in operation, the later 2012 MacBookPro 15" i7 has a failed graphics chip - a known issue - so until I can get Louis Rossman to fix it it remains a dead Mac, it has ceased to be...
I'd recently installed Manjaro KDE on my original 2009 (2.52GHz Core Duo 8Gb RAM 250Gb SSD) laptop and it recognised the hardware, everything worked although the WiFi was a bit glitchy on startup. Also it would freeze from time to time. Maybe KDE was too much for it. How about if I installed ElementaryOS 6 since I have ElementaryOS 5 Juno on my Thinkpad X230 without any issues... Elementary is not specifically a lowend Linux distro designed for old machines, but it IS a Linux distro after all (less drain on resources) and Pantheon resembles the Mac OS look. I've never had any issues with Elementary and hardware (apart from Bluetooth sending files).
However, sadly, ElementaryOS 6 Odin didn't play well on my old MacBookPro. The wireless was absent and even the ethernet connection was flickering on and off. I did the usual updates but I noticed as others have remarked it comes with precious little in the 'curated' repository. The fan went wild and the machine froze several times. Overall it was annoying enough for me to abandon the experiment and determine to try Manjaro XFCE. I don't know whether this was an Elementary issue or specifically an Odin issue. But others have this issue.
When I studied digital media at college one of the tutors told me something I've never forgotten and has saved me hours of hassle: if some piece of software isn't working, don't spend too long trying to troubleshoot, there's plenty of choice out there - move onto to something that works. This is an excellent smartworking attitude. In this instance I had an old 2009 13" MacBookPro with 8Gb RAM and an SSD. I had several suggestions for Linux distros that would work on an old Mac - except they didn't, certainly not out of the box: