Hello JTrinh03
Yes, the Friends Day Pass for Youth is also available for foreigners. The only condition, everyone has to be under 25 years (24.99 years of age).
Friends Day Pass for Youth. | SBB
However, if you plan to visit the Jungfraujoch, the Swiss Half Fare Card is strongly recommended. The high ticket costs for a full fare ticket legitimates its purchase. And, my advice, do not buy Jungfraujoch tickets in advance. It would mean a waste of money if the weather is not favourable.
Kind regards,
Roland