I'd not trust 10 year old Di2 kit only because of the potential difficulty finding a replacement part should one fail...and the cost of the replacement part may be quite high.
As said I'd check with local bike shops to see what they offer as well as asking about local riding clubs/groups/etc. You may learn the most riding with other like minded people and have a lot more fun doing it.

I'm still on 11 speed Ultegra mechanical...by choice. Even though I get my parts wholesale it is still expensive to outfit a bike with a Di2 system and I had a perfectly good mechanical set ready to use. I'm even using mechanical disk brakes...TRP's carbon calipers are quite good though a bit costly. While not as smooth and requiring a bit more strength to use they work fine.

Di2 kit works great and I've worked on and built many a bike with Di2 but mechanical still has a place so don't discount it.
Enjoy riding no matter the bike...