remy VS maxio

What I do is I create backups with rsync (so "low-level" backups of the actual data the tablet is using to represent the notebooks, not just the rendered pdf). Then I use Remy to browse them if needed. (Disclaimer: I'm the developer of Remy) It currently lacks a way to export/import the notebooks in native formats (that would allow you to restore archived ones through the GUI) so if you need that you need to do it manually, which requires some basic knowledge of how the notebooks are internally stored.

reMy and RCU are the best alternative desktop clients. The former has a focus on notebooks, while the latter is focused on ease-of-use and does it all (templates/notebooks/wallpaper/and much more). Both use their own rendering engine for custom PDF export options. Neither installs anything to your tablet, so they usually work through software updates. (Disclaimer: I am the author of RCU).

You can also take backups using easy, convenient, community-written software, like RCU (which I'm the author of), reMy, reMarkable HyUtilities, rmExplorer, rmAPI, and many others found in the Awesome reMarkable list.

You could use something local, that uploads over SSH instead of the Web UI. The Web UI and rM Cloud choke on files over a few hundred MBs. reMy + 2.x firmware might be what you're looking for -- it has sync capability. (I assume OneDrive has something like a shared PC folder that you can use as the target directory.)

You could try reMy, which has its own renderer. There are more rendering programs in the Awesome reMarkable list, many of which will work with 2.15 and below--just avoid anything saying 'cloud' or 'web UI'.

Mathpix has this functionality and is cheap. I integrated it into Remy, see here for a demo (although it's a bit outdated, the app has now way more features). It's not a fully fledged integration, I was planning to use it for having a search index that could match on handwriting but had no time to implement it.

If you need support for the new v3 software update, not sure. Otherwise Remy can do that for you

I use my own Remy tool (in conjunction with rsync for backups). Unfortunately it is not working with v3 just yet but I plan to eventually add support for it, once the effort to reverse engineer the new file format settles.

You're not alone :-); we started discussing it here https://github.com/bordaigorl/remy/issues/49

But parsing and rendering are two different things. RCU used to use the remy parsing, while the developer put considererable effort into the rendering himself. Yet he wasn't satisfied (I was) and started to completely rebuild it. That's where he lost interest in RCU :-(

I added an rm2svg (and rm2pdf) converter to rmscene (see pull request here), and then added glue for maxio (the package I use for conversion) to resort to rmscene for version=6 files (see pull request here). The setup is cumbersome (you need to download both repos in the same root directory, as maxio will look for ../rmscene/), but I'm not sure whether the upstream repo owners are interested in any of this work, or whether they're willing to unify their repos (which IMO is the right solution).

pick your favorite solution from e.g https://github.com/reHackable/awesome-reMarkable#lines-format to convert the native Lines format to PDF or SVG. I personally use https://github.com/lschwetlick/maxio/blob/master/rm_tools/rM2svg.py in my scripts

You might be interested in https://github.com/lschwetlick/maxio/tree/master/rm_tools also.

Not sure I understand as the reMarkable doesn't have an image viewer. That being said here are some examples using scp https://gist.github.com/Utopiah/e2d5c944bbd632e3ae0530e602977f45#file-remarkable_functions-sh and specifically for conversion https://github.com/bsdz/remarkable-layers https://github.com/lschwetlick/maxio/blob/master/rm_tools/rM2svg.py