The former approach ("pipe")
/usr/bin/yes YES | /usr/sbin/sensors-detect
seems to work.
/usr/sbin/sensors-detect <(/usr/bin/yes YES)
just hangs ... even when executed, from the console, outside of a script.
Since the pipe technique works (and I understand it ... I swear I did try it that way, earlier ... sigh), that's what I'm going with ("Ship it!").
As to why the latter does not work, I haven't a clue: a learning experience for the future.
Thank you for your advice and help! I very much appreciate it.