here this is how it would be setup
pfsense --- vlan20T, vlan1U --- switch --- vlan20U --- pc
The pvid settings on these ports would be 1 for where vlan 1 is untaged connected to pfsense, the pvid for port connected to pc would be 20..
Some switches do this without any way for you to edit it, other do not..
All a pvid does its tell the switch traffic without a tag that is entering this port from the network will be on this Vlan..
Does pfsense see the dhcp discover from your PC? If not then yeah you got something wrong and no your never going to hand it an IP.. You sure dhcpd is running on your vlan interface, etc.
You sure your switch is actually in dot1q mode vs port mode for vlans?