How to separate real-gunpla models to parts in Blender:
1. Enter Edit Mode, select all vertices
2. Mark all off them as sharp (Edit Mode - Ctrl+E - Mark Sharp) (not necessary, but without that all of the parts will look fucking ugly in Blender)
3.Press RMB - Merge - By Distance
4. Press P - By Loose Parts

https://i.4cdn.org/m/1697739343602180.png