There's an option for scaling_factor which increases the size of dots through multiplication (I think?), but if the value is 0 (or np.nan), it will not be visible on the map.
For instance, here is a map of stations with size_index set to the precipitation column.

Somewhere in Alaska gets a lot of rain! I think this is addressed by https://github.com/ioam/holoviews/pull/2152 , which I hope can be resurrected and merged someday soon!
I've made a good bit of progress on https://github.com/ioam/holoviews/pull/2152 and it should be able to land in 1.11.
I'll close this since it's covered by the op proposal.
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Somewhere in Alaska gets a lot of rain! I think this is addressed by https://github.com/ioam/holoviews/pull/2152 , which I hope can be resurrected and merged someday soon!