This Reddit post Responsive Design for Datatable in LWC or other UI Suggestions? includes this quote with no links or details:
The salesforce data table was just redesigned to be responsive. The component team shared it at TDX. I'd wait until you try it this release before spending time creating your own or investing in a 3rd party.
I had a brief look at the TDX recordings and the Summer '24 release notes but didn't find any mention of this. The classes slds-max-medium-table_stacked
and slds-max-medium-table_stacked-horizontal
have been present for some time and do have an effect but are not well documented.
Will there be a responsive datatable component soon?
PS
Did some more Googling and found this session recording Elevate Your User Experience with Screen Flows | TrailblazerDX 2024. There the flow-specific Datatable is discussed, though not in the sense of working on small screens. So I suspect that the answer to this question posed here - a responsive lightning-datatable
LWC - is No.