As the title notes, Microsoft has made the Microsoft Ignite event this year free to attend. Scheduled for September 22-24, 2020, it will feature more than 700 sessions on all aspects of the Microsoft technology stack. You can read a preview of the event in Redmond Magazine here: https://redmondmag.com/articles/2020/09/17/microsoft-ignite-2020-preview.aspx
You can register here: https://myignite.microsoft.com/home
I also saw a post from Sharegate about their picks for the top sessions on Teams and securing Microsoft 365. You can find that post here: https://sharegate.com/blog/ignite-2020-sessions-manage-secure-teams-microsoft-365