Does setting the WB offset in the picture profile settings have the same effect as balancing on colored cards? Can it be used in place of warm/cold cards?

Well since you can adjust Kelvins manually to whatever you want you pretty much have full control.

Occasionally I measure the white balance first, go into picture profile settings and adjust the white balance manually (higher Kelvin setting to make the picture warmer) and after that I use this preset setting. Works fine.

regards,
Erwin