Documents on the reMarkable can be exported to PDF, PNG and SVG through the “send files via email” feature on the reMarkable tablet itself or through the reMarkable Client.
3rd party applications like rmapi can also export files to PDF, but are not as feature complete as the solution provided by reMarkable.
If one wants documents looking exactly like on the reMarkable tablet, PNG is preferable. Note that this also means it contains the flaws of looking exactly like on the reMarkable tablet.
While PNGs are (compressed) raster images and get displayed the same way regardless of the image viewer, PDFs are a bit more complicated.
PDF documents exported through the desktop application aren't much different from the ones exported from the reMarkable. 1)
One might think that documents with templates exported by reMarkable products are rubbish, but it is most likely due to the specific document viewer used, and how it interprets and displays documents.
This kind of issue is most visible with the small grid template and Firefox 92: 2)
Document viewers that are known to have acceptable results are:
Tested versions and OSes are specified for sake of accuracy.
It is preferable to view it at a pixel to pixel (1:1) size (not zoomed in). 4)
If enough width is available, the browser should display it at 1:1 on this page.