According to a new Nikkei report, HORI has sold about 2000 units of Flex Controller for Nintendo Switch since its launch in Nov 2020. About half of the sales were overseas.
No idea whether the number is good or bad. I suspect that some potential users who need this might not be able to afford the $250/¥24200 price tag.

[Originally posted on 2025-09-26 Pacific Time]