You should look into installing linux on your mac. It might be possible to have linux installed side by side along with your macOS. Or just get linux as your macos is no longer supported anyways. Or get linux, get GOS, then restore back to macos. Supported linux are in the prerequisites too.
If you have another android phone you can use that to install without a computer. But it needs to be Android 13, 14, 15 and 16 with Play Protect certification.