Ok! Hopefully you haven’t saved much before this and you can salvage what you have before ‘ideally’ formatting as Portable/External.
One major issue seemingly obscure but understandably, is that if an SD card is formatted as an extension to the internal memory then the contents are encrypted and if the phone ‘dies’ or needs a factory reset for a check or a repair then the SD card contents are lost or wiped.
I doubt it. I tend to move Whatsapp images I want to keep to my Externaly formatted SD, don’t forget if you have to reste the phone etc. you loose all data anyway on an Internaly formatted SD card.
Regarding WhatsApp, can yo, aren’t they save by WhatsApp on some cloud, or you can upload them to such.
Regarding the camera. If you are using the default camera app, you can select where to store the images, so no need in future to move them.
As for what is lost. is lost most likely. I’ve seen no reasonable way of retrieving from SD cards that are not acting as expected under Internal formatting, after all the card is encrypted.