This is possible via switch that does vlans and support dynamic vlans, or wifi again that supports via radius or 802.1x etc..
This has always been possible - but really has zero to do with pfsense.. This is your switching/networking infrastructure to put your devices/users on different vlans… Once your devices are on different vlans then pfsense comes into play and can firewall that vlan from different vlan or allow network/vlan X to use wan 1 while vlan Y users wan 2.
You don't need to be on different vlans to control which wan a connection goes out of - you can do this with policy routing based upon the IP all in the same vlan.. So IP 192.168.1.100 could go out wan 1, while 192.168.1.101 goes out wan 2, etc.
Whatever method you want to use to make sure user X gets a specific IP works too - say radius auth handing user specific IP vs vlan ID, etc. But all of that is your network and not pfsense.