koreanfromzero.com Available as free interactive online content, downloadable pdf, or printed textbook.
Tuttle Publishing--All kinds of language learning books, including textbook courses, supplements such dictionaries and alphabet practice, literature for language learners, crafts, history, culture, etc. Specializing in Asian languages.
https://www.tuttlepublishing.com/brands/Language.html
ASL
Signing Online--appears to be set up similar to college credit, includes all the standard components of a full course such as vocabulary, grammar, culture, receptive and expressive practice, etc.
www.signingonline.com
LifePrint
www.lifeprint.com
Free self-study ASL lessons...for some reason, my dd didn't like these, but they are free to explore to find out.
---------- Post added at 01:28 PM ---------- Previous post was at 01:24 PM ----------
Spanish
https://www.pbs.org/show/salsa/ Immersive video (all Spanish, no English) Geared toward elementary. Designed to be comprehensible for beginners. Uses familiar stories such as Goldilocks. Kind of like Sesame Street.