Yup totally fair - would likely require you upload the images manually for pure client-side. You might still be able to offset a portion of the compute by just

Yup totally fair - would likely require you upload the images manually for pure client-side. You might still be able to offset a portion of the compute by just figuring out the URLs of the images on the back-end, sending that list to the client, which would then download and do the optimization / resizing.