I fitted a Chinese unit and it’s been great - as have many of my friends.
Sure they’re not the last word in sound quality but perfectly good enough, and will probably be an improvement over your current OEM items with much improved functionality.
I forget the name of the one I’ve got, I think it’s Xtrons or something like that, it was an eBay special. Fits in the dash well and looks fairly OEM. I’d definitely get another if I changed car ect.
You could of course retro fit the OEM nav set up - I have done this previously to another car and it’s quite a mission but perfectly do able, but costly, a lot of effort and the end result isn’t that good In terms of features or SQ, so not the best option unless you must have OEM at any cost, which for that particular car I did.
You could just add a Grom audio BT3 to your current set up, you’d lose the Cd changer option but gain music streaming and hands free calls, fitting is easy and they’re only about £130.