Why a German invasion of Sweden would become a strategic burden

What if Germany invaded Sweden while taking Norway in 1940?

Germany might eventually occupy Sweden, but the cost in troops, logistics, politics, and iron supply would make it a damaging strategic choice and could delay France.

Sweden's geography is poorly suited to a quick blitzkrieg, and occupation would likely face a brutal resistance campaign. A simultaneous campaign would delay other operations, disrupt extraction, and cut against German relations with Finland, making the prospect far less attractive than a map-only comparison suggests. Germany would need to attack through Denmark and Norway because the Swedish Navy could contest a direct landing outside the controlled Danish belts. Even a successful occupation could sabotage the iron-ore supply whose security made Swedish neutrality valuable in the first place.