I have bought bulk 10" White Spruce plugs https://chiefrivernursery.com/..., they are 1 year old. The pots I have are either 1 gallon or 5 gallon. We all know they are actually less than 1 gallon (i think is more like 0.66 gallon). https://www.amazon.com/dp/B0055PERPO/ If I plant into the 1 gallon, approx how tall and long should I expect these Spruce to do well in that size of pot? thank you

I'd go for the 5 gallons specially if you are planning to have them in there for more than one season. Getting pot bound in a one gallon pot is extremely easy. Also in the one gallon pots you will have to water a lot, specially on the heat of summer.