Alternatives to Volvo Navi

Hello together, so first of all praise to the forum, I have already received a lot of useful hints. In the end this has also led me to order an XC70 Mom./ D5 in blue 4 weeks ago. However, I find that the original Navi with its performance is much too expensive. Therefore I will retrofit. First I was with a TomTom GO 700. But now I see that you get already under €1000 a fully-fledged Navicomputer with 7-inch screen. Sounds good … only, how does it look with the installation? Does the XC have a DIN shaft? Do I then need apertures, adapters? How is this with the cable, can I/man do something like that yourself? What do you think about theft when there is always such a TFT in the car? Isn’t this a temptation (living in Frankfurt)? Your opinion would interest me. Greet NN P.S.: Be happy already like a small child on the elk!!!