Bold of them to threaten Sweden. They're just going to go full Viking and drive a fleet of old Volvos blaring death metal while Saabs bomb the hell out of them from overhead. Finland will just cut off their supply of vodka to Russia and then go sit in a sauna.
But ya, I don't think Putin learned anything from presumably having a history class. If you spread your forces too thin, you're going to get steamrolled. I don't know about Finland, but Sweden has better military hardware than Ukraine along with much tougher terrain even though their force is likely smaller in number. They can also cut off the Baltic Sea (along with Finland) and cripple St. Petersburg and Kaliningrad. I know Sweden is neutral when it comes to military matters though so it doesn't really have allies to lean on, but I'd have to imagine if Putin starts waving his little willy around in Europe too much that's going to change.