In a filing, prosecutors have said that they are currently extracting data from locked phones seized from over 100 alleged rioters:

In new filings, prosecutors told a court in Washington, DC that within the coming weeks, they expect to extract all data from the seized cellphones of more than 100 allegedly violent protesters arrested during the inauguration of President Donald Trump. Prosecutors also said that this search is validated by recently issued warrants. [...] "All of the Rioter Cell Phones were locked, which requires more time-sensitive efforts to try to obtain the data," Jennifer Kerkhoff, an assistant United States attorney, wrote.

Also at BuzzFeed, CNET, and The Verge.