It is possible to create a keyboard mapping for File->Stream Export but not Pattern (selection)->Render to Wave.

The latter automatically confines playback to selected patterns. This has to be done manually by setting "From position X to Y" if you use the currently available Stream Export shortcut which defaults to "Play entire song".

Additionally, it would be extra nice for the workflow to be able to 1) quickly render any portion of the song directly into a sample (possibly accepting selection from either order list or pattern editor, since those seem to be mutually exclusive?), or at least 2) have the Export window remember your last choice for File/Sample Slot/which slot. This would save time and clicks for people who often do sample baking.