Just a note, do not let the game "pressure" you, there are at least 2 occasions, where you are urged to not keep an NPC "waiting". This might cause you to reach the end too quickly. There is no need to start the "endgame" until you have done all the "side quests" and Gigs, the NPC will wait.
Just a few numbers, the main story has 30 "missions" . There are 92 side quests and a total of 86 "Gigs" spread through Night City and the surrounding area. There are 37 in game vehicles to obtain and 190 "hidden gems" small interesting hidden stashes and set pieces, that do tell stories, but you would probably never find all of them with a little help. So if you want the complete experience don't finish the game till the map is empty ;-)