Buying shares of a reputable foreign company on the US pink sheets is relatively easy and painless; I did this with NVS before it listed on the NYSE in 2000.
To ensure that you don’t overpay for Medivir, buy after the market closes in Stockholm; take the closing price in Stockholm*, convert from Swedish kronor to US dollars, and submit a limit order to buy close to that price.
Medivir’s market cap at Wednesday’s close in Stockholm was 4.24M Swedish kronor = $652M. This does seem low, but I haven’t examined the balance sheet to what the rest of the company’s capitalization looks like.