OLTP - Stretch database vs linked server
Limitations for Stretch Database

Not all tables will be eligible for being Stretch-enabled. Certain table properties, data and column types, constraints, and indexes are not supported, such as:

Memory-optimized and replicated tables
Tables that contain FILESTREAM data, use Change Tracking or Change Data
Data types such as timestamp, sql_variant, XML, geography or columns that are Always Encrypted
Check and default constraints or foreign key constraints that reference the table
XML, full-text, spatial, clustered columnstore and indexed views that reference the Stretch-enabled table
You cannot run UPDATE or DELETE statements, or run CREATE INDEX or ALTER INDEX operations on a Stretch-enabled table