With VSC, the only extensions are those MS builds API's for. It's hub and spoke integration, for a few big leaders and many tiny followers.
With Eclipse (Theia or otherwise), it's fully open, with a large number of medium-sized groups. There's much more flexibility, but more opportunity for integration trouble (and more appreciation for those who do it right).
The ecosystem has benefited from Java's open-sourcing and becoming the default organization e.g., for jakarta, but it never really recovered from the loss of IBM as the big dog driving enterprise (or the transition to Eclipse 4 style UI's).
With Eclipse (Theia or otherwise), it's fully open, with a large number of medium-sized groups. There's much more flexibility, but more opportunity for integration trouble (and more appreciation for those who do it right).
The ecosystem has benefited from Java's open-sourcing and becoming the default organization e.g., for jakarta, but it never really recovered from the loss of IBM as the big dog driving enterprise (or the transition to Eclipse 4 style UI's).