Make it so that Item types can be defined as being local only. I do not know if this would be done easiest by have a flag for each item for whether they should be synced or local only, or if an actual Item library could be made for each Teamhood board. My thoughts is that for e.g. developers working in Azure DevOps system, many project admin deliverables and such is irrelevant and would simply clutter the ADO system. Therefore the Project Manager could keep such items locally in the Teamhood workspace / gantt chart. Furthermore this would also solve the issue of Milestones and Gates being able to be Teamhood exclusive items, as then you could simply flag any item in Teamhood to be local only, and then flag it to be a Milestone, etc.