4809 self programming

Anyone messed with self programming a 4809?
I have one hooked up to a 16u2 for usart connection and i want to be able to send code to the 4809 using serial from avrdude.

Obviously updi would be easier but i have specific code on the 16u2 i dont want to mess with.

It appears that my best course of action is to modify the bootloader so its compatible with the 4809?
That way it can re-write the flash over serial?

Any existing examples of this?
I can't find any/seems like it might be a issue to do?

Oh I'm having fun with the 0 and 1 series tiny chips... not... make sure you get the newest datasheet from 15 Aug 2019. Many improvements but so many changes...

Yeah its definitely a learning curve for me that is causing a lot of headaches lol

I plan on spending some time with it before I can trust it...

Some relevant discussion: