A lot of them seem to be “free” with an optional subscription.
Like for making PDFs of physical documents? It’s not open source, but the Google Drive app can scan documents. It works fine, in my experience.
Yeah, Drive is one option but I’m hoping for something where I can just save PDFs to the device or share directly rather than saving to Drive.
I know its not foss and Microsoft is the devil but Office lens let’s you save to the device directly in a lot of formats like pdf, word or as pictures
Also evil, but the Adobe scanner does similar
Not sure if evil or not, but Dropbox also has a nice scanning feature. It goes to the cloud, but you can download the PDFs after creating them. And there is a free tier.
I haven’t used them but these are on the izzysoft F-Droid repo:
Use Clear Scan with internet permission blocked or removed. Nothing will trouble you further.
I currently use Notebloc. It’s not opesource and has ads. But it’s decent.
You may try this: https://github.com/Akylas/com.akylas.documentscanner
I don’t know if the grapheneOS camera lets you scan anything (phone lost charge) but it might since it also has a QR code scanner option. Have you searched Fdroid?