I've been very happy with 1dollarscan. They make a nice pdf file. I use ABBYY Transformer to convert pdf file to epub (and you can use Calibre to convert that to a kindle format if you need that). Unfortunately, it seems they no longer sell that and switched to only selling their more expensive product ABBYY Finereader. It's a more robust product, but also has a higher learning curve than Transformer did.
They take books or magazines, not pdf files. However, you can have those delivered direct to their offices and then download to your computer when done. If you have questions, I'd send them an email for more direction. Just like every other place, they are probably slowed up because of COVID issues.
Here is contact info.
https://1dollarscan.com/contact.php