The SP 4 has only one USB port - a rather ridiculous choice in this day and age but there we are.
It does not deliver enough power to that port to reliably run a Lexar card reader (according to Lexar).
I also use a mouse that needs a USB dongle.
What is the best, travel friendly and most cost effective way to add more USB 3 ports, ideally with adequate power to run the card reader?