While your model may not be supported now, it may be in the future. I would join some of the communities that make custom roms and operating systems and lurk a bit to see if someone is doing a port to your phone and are near the stage where they need testers.

Look at deGoogle guides to see what you can do to make your phone safer in the mean time. Every little bit can help you be more secure.

I grew up with my brother throwing used computer parts on my bed whenever he upgraded something, in case I wanted to reuse them. He also gave me a copy of Windows 98, and later XP that I reused every time I did a major hw upgrade. But one day the XP CD-rom was just too old, but I was too young to start working and had no money, and so Linux came into my life.