Buying Recuva Pro will make no difference, it’s the same recovery as the free version.
You may be able to fix your files simply by using a particular image viewer.
Users have found that often Irfanview can open such incomplete (or damaged) files.
Irfanview is much more tolerant than most viewers are about opening slightly damaged image files.
If Irfanview can open them then saving them again from Irfanview fixes the files so that other viewers can then open them too.
Irfanview is free: https://www.irfanview.com/
PS. If Irfanview won’t simply open them as they are then there are other ways to try and fix them.
One way is to convert the file fromat from jpg to another image format.
Irfanview can do that too (even on images that won’t open) using it’s ‘Batch Conversion/Rename’ tool in the ‘File’ menu.
If you have to try that then make a copy of the damaged files first and work on the copy, that way if you mess something up you still have the original so can make another copy and try again…