1024kb: If you do want MacOS back, go for an early version - Sierra, High Sierra or Mojave. They're lighter on system demand & will install on older devices.
Once you've got the earlier OS installed, update to wherever you want to be through Mac's update facility.
Do you have another Mac available? You'll need one to create a bootable USB. If you haven't got access to another Mac, then get TransMac for your Windows install - that'll do it for ya.
I *think* Balena Etcher might handle writing bootable MacOS USB drives from Windows too.
Let me know if you need links to known-good MacOS files.
OK, thanks. I'll give Mojave a go.
I've found the DMG file. https://isoriver.com/download-your-file-now/?url=https://archive.org/download/macOS_Mojave/macOS_Mojave.dmg


