That's exactly what my team did at a former company. We generated reports through a legacy document engine because some customers cannot switch/update their rep

That's exactly what my team did at a former company. We generated reports through a legacy document engine because some customers cannot switch/update their report templates and so we moved the logic out of the monolith into a service to get rid of a large portion of our dependencies. Moved the monolith to .NET Core, kept the report service on .NET Framework. A win for everybody.