pkg add -f netbird-0.28.3-whatever.pkg
sysrc netbird_enable=YES
service netbird start
netbird up -m https://netbirdhost -k netbirdkey -interface-name tun12
create new interface, assign to tun12
find netbird ip with netbird status
set static IP to your netbird ip /24
create a gateway, also use your netbird ip
create firewall rules allow all ipv4 protocols on new interface

add service netbird start as an shellcmd
add netbird up as a shellcmd

to install pfsense netbird UI install package https://repo.nhdit.com/netbird-pfsense//pfSense-pkg-netbird-0.0.2_30-amdv2.pkg or the arm one, either way. Then netbird will show under vpn menu. This is not complete.