@enboig
I found out that the best way to connect your PC (or Raspbery Pi) to your Network is with a LAN-Cable. Most (even old Computers) will have a LAN-Port built in.
It's way faster than WLAN if you want to put new ROMs on your System.
For WLAN-Dongles look here:
https://wiki.recalbox.com/en/hardware-compatibility/compatible-devices/wifi-dongles
These Dongles are "official" compatible with Recalbox.
For compatible Bluetooth-Dongles look here:
https://wiki.recalbox.com/en/hardware-compatibility/compatible-devices/usb-dongles
Sure, you can buy a PCI-Card, but it's not guaranteed that it will work with Recalbox.
I would suggest that you connect your PC with a LAN-Cabel to your Network an buy a wired USB-Gamepad (like the Logitech F310 - I own it myself and it works great).
That will spare you a lot of Trouble, especially with the new Versions of Recalbox.