Apple Photos app corrupts images

Your workflow was horrendous, and now it's merely bad. Don't touch any images on the card until you're sure that the images imported correctly AND your local and cloud backups have backed up the images. I assume you have local and cloud backups. If not, you should set them up right away. Really, cards hold a huge number of images and there should be no rush to empty them out.

Yeah it really amused me that he went through tons of steps, buying lots of new hardware, etc before simply unchecking the delete images box.

That the workflow could be better does not really excuse the software corrupting the images. This is like the "you are holding it wrong" type excuse.

You also shouldn't delete from the SD card using your laptop anyway. Always use the in-camera format. This was a bad workflow from the beginning, no idea why you would ever click "Delete after import" when importing directly off an SD card.

Also a good idea to copy to multiple locations when importing. When I do professional work and import into Lightroom from SD card I have it set to create two copies - import to my external SSD (the "working" copy) and also copies the files to my NAS (which is then backed up to the cloud).

Nowhere in that process do I ever delete anything.

This bug is clearly Apple's fault, but no matter which software or OS you switch to, you'll encounter a bug eventually and you'll be glad to have a workflow that is resilient to that.