Both Google Drive and Dropbox mobile apps have built-in multi-page scan-to-PDF functionality
I've still been labouring recently with a standalone scan-to-PDF app until my non-tech sister pointed out she has been using the Dropbox app for this for ages now (maybe because I mostly use NextCloud?).
Google Drive takes a plain photo (in the app) and you can rotate (pinch gestures too), crop, and change the colour type (B&W, Colour, Colour drawing for each individual captured image). You can optionally hit the + button to add more pages. Each page can be rotated individually but I do not see an option to re-arrange the order of the pages. It then prompts you where to save it on Drive.
Dropbox starts out the same but captures differently in that you point the camera at a piece of paper (even if it is skew) and it will identify the edges of the paper and capture automatically to show a preview which you can then adjust between original, B&W or Whiteboard also per page (with a contrast slider for the two non-original options). It also offers rotation and addition of additional pages, where you can then rearrange the order of the pages (individual pages can be rotated). It also finishes off with prompting to save to a location on Dropbox storage.
So key differences are Dropbox can be quick to capture if the pages are easily discernable from the background for auto-capture (pressing the capture buttons no edge differentiation but you can adjust manually afterwards) and it has the page re-arrange functionality. On similar white on white backgrounds, neither app could discern the edges properly. They will both do multipage scanning though as well as automatic de-skewing so it may just come down to which storage service you prefer to use.
That said neither of these apps is specialised at what they do and some of the paid scan to PDF apps offer advanced functionality with document types, image correction, etc.
#scan2PDF #PDF