It is widely known that SMUI is broken with SvelteKit/PNPM.
You get can't find stylesheet to import errors regarding various sub-modules in material.
To get around this you have to manually install those missing sub-modules @material/* into the top level node_modules.
For more info on the workaround, see issue-348
I repeatedly ran
pnpm run prepare
and then
pnpm i -d @material/[name]
for whatever came up as missing for the prepare.
I only added enough to get Button, Card and Drawer working.