For AD accounts, I'm adding the account in the data source to the local admins group that SSRS lives on (different than the sql box I'm querying data on) which works. I think theres also a scaled down permission to make the magic happen through the Local Security Policy but need one of my sysadmins to make the change to test.
For sql authenticated accounts I can work around it by adding "TrustServerCertificate=True" to the end of the connection string, but that's not a good perm solution. The internet suggests "You likely don't have a Certificate Authority(CA)-signed certificate installed in your SQL VM's trusted root store." Waiting on my sysadmin for assistance on this as well.
Figured I'd post my findings for others w the same issue.