HADR solutions for SQL Server 2016 Standard Edition
Log Shipping for DR.  Not so much HA as no automatic failover, but still better than nothing.   Use Windows cluster for HA, and Log ship them to somewhere else.

transactional replication IS allowed in standard:
https://docs.microsoft.com/en-us/sql/sql-server/editions-and-supported-features-for-sql-server-2016#a-namereplicationa-replication

But is not really an HADR solution