Using the new {$targetpath} (thanks again! 
), I created a button to move an image file and then convert it. Here's the button code:
Go /favs FOLDERCONTENT=move,nofiles,showempty,resolvedirlinks
[
Image CONVERT FROM "{$targetpath}\{file}" PRESERVEDATE PRESET="2048x2048 (Replace)"
]
It does work as expected, but only for a single file.
When multiple files are selected, all are moved, but only the last one is renamed. In Batch for loop with filename code {allfile}, @Leo says that using a variable like {file} should automatically loop through all files. Is this not the case in embedded commands?
Btw, {allfile} contains all selected filenames, so maybe as a workaround it's possible to write a manual loop? (for file in allfiles → convert)