I tried to find a pattern that could potentially look like it was embroidered by hand... I think handicrafts like sewing and needlework might make a comeback in the absence of a large-scale clothing manufacturing industry (that wasn't connected to the military, that is). Big cities like Mora and Reykjavik might have several tailor shops that sell handmade items, but people in smaller settlements like Keuruu probably would do their own sewing.
I think you're right about the hand-sewing. But looking at the beautiful (and large-scale) flowered pattern, I think it would be more efficient to produce by block-printing with layers of dye. Printed fabrics predate the Industrial Revolution by hundreds of years -- e.g. Indonesian batik, Indian muslins, and Pacific/Maori paint-stamped tapa cloths. (Not to mention French toiles.)
On the other hand, would Finnish society approve of such frivolity?
I got a faintly Communist vibe from our brief view of Keuruu and Finnish transportation -- the Mao jackets and Tractor Girl part, not the ruthless repression part -- and Minna's statement that Tuuri's and Lalli's blue-and-white tunics and other clothes were standard Army wear: "cheap, plain, and practical."
But we're seeing the Finns at the start of winter, when they're all dressing to defend against cold weather. Maybe they all break out the pink-and-red Marimekko prints, strappy sandals, and board shorts once summer comes? (Except for Onni. He will continue to wear his parka all summer, because he's afraid of skin cancer.)