Surely you can download the extension from a mirror and install it manually(ie the "old fashioned way")?
Dead Comment
I remember from the early 2000s you could get railway time tables from the German railways for your selected pair of stations as a midlet. That was truly useful.
I also used a mobile browser frontend. The data was rendered by the backend and transferred in compressed form. That was very usable at 2G speeds. Of course JavaScript was rare at the time. But I don't think the product was any commercial success.
Of cause their were (mostly toy) games. But in general the technology was probably 10+ years too early for the market.