Using a dashboard variable in Table panel 'Filter data by values' transformation

It is possible now:

‘Filter data by values’ transformation, was not directly supported in Grafana 8. This functionality was introduced in later versions of Grafana, and so it has been possible for some time now, as of 10.2.

To use this feature, you would need to upgrade to a more recent version of Grafana (>=10.2 or later) and enable the feature toggle.

But for example using Grafana Cloud this should be possible right now, today, just as the question poses.