You have created a custom object to list all upcoming company events, including speaker bio's...

Go into the Community Page Manager and update the Page Access control to Public

Go into the Setup Menu >> Profiles >> edit the object settings on the guest community profile

Add the sample code provided on help.salesforce.com to the head markup and add the object name you want to expose publicly

Install the Community Object Permissions Manager from the AppExchange for advanced data sharing options

Go into the Community Manager and select the objects that are available publicly

Go into the Community Builder and navigate to settings and click on the hyperlink to the Guest User Profile