What I mean by openly demonstrated to work is some sort of public demo that would require use of the inter-satellite links. The linked article just says they've started testing and been able to move data, which means nothing about how well it actually works.
I'd even be satisfied by specific claims of test results that could be validated once the capability is officially activated.
They did a test in late 2020[0], and all launches since June 2021 have been Starlink v1.5 with lasers[1].
0: https://wccftech.com/spacex-starlink-satellite-laser-test/
1: https://en.wikipedia.org/wiki/List_of_Starlink_launches