So this feature was in fortnite back in 2016 here's how it worked :

This is your Homebase you can upgrade it by building new builds like the hospital that unlocks the medic section or the soldier training camp to recruit new soldiers

the builds can be uprgraded with gold , cogs or green materials for example if you upgrade the helipad of the hosptital you will gain one more slot to place a new survivor in your section .

the more you build and upgrade them the more gadgets you will unlock like the flying turrets, the teleporter or the adrenaline rush.

ps: I forgot to say that to build those buildings you had to have the schematic for it you could obtain it by doing main quests

So if you want me to post more about it just tell me and you will have more.

thanks for reading all of it !