Early 2009 iMac OS

Hi,

I have an old early 2009 24 inch iMac currently running El Capitan 10.11.6, and I saw this iMac model is not supported anymore in the newer OS versions distributed by Apple. Since I don't want to run an unsupported version of the OS which will soon stop receiving security updates, I am kind of stuck.

Considering I already did a RAM upgrade from 4GB to 8GB, and the hardware seems to still be running fine, I thought I could try and change the Operating System instead of trashing or reselling the machine. What are my best options to go on with this computer?

I've seen other people talking about hacking the EFI and firmware update to somehow be able to run Sierra on unsupported device, but I'm not fond of the idea.

As a regular Windows user in my professional life, I could cope with removing macOS entirely to install Windows 10, if the driver support was good. But I am concerned with Windows 10 driver support. Especially since I read I would need Bootcamp to install Windows in such a way, but there is no Bootcamp support for Windows 10. Did anybody try this and could they share their impressions on such an update?

As a former Linux user, I could also be comfortable with the idea of installing a Linux distro, if driver support for that model is good enough.

If needed, I think I still have the OSX installation disk somewhere.

PS : As a side note, I am not attached to any specific software on this iMac anymore. I used to be a happy user of the old iLife suite (iPhoto, iMovie, iDVD, iWeb), and the Time Machine backups. At some point I even started using iWork for the cross device support. But ever since iPhoto was dropped in favor of the new iOS Photo, I've been trying to get rid of any software developped by Apple. I am still using iTunes occasionnally for synchronizing with other iOS devices, but I could install that on anything else.