There’s also this Feature Request about “Resize to Current Layer” that has an extensive discussion in it:
Request for Resize to Current Layer function
I’d have the following comments on your initial statements:
Trim to Current Layer does expand the canvas, with the consequence of deleting all content outside the final expanded canvas size.
How is that different from a general ‘Resize Canvas to Fit All Content’ that would either expand or contract the canvas size as needed?
That says that a command called ‘Resize’ performs a ‘trim’ action.
The words ‘Resize’ and ‘Trim’ are normally used for actions with distinct results regarding any removal of content.
A better term would be “Trim Canvas to Fit All Content”