Thanks for the suggestions. However, they all have issues:
xli - doesn't support zooming with mouse wheel
xloadimage - doesn't support zooming with mouse wheel
geeqie - has UI rendering issues (not all text visible); uses dbus
gthumb - uses dbus
mirage - core dumped on me (Ubuntu 22.04 package, remote X session)
display - doesn't support zooming with mouse wheel
My images are usually too large to fit on a screen 1:1, so zooming is essential.