I'd also like to push back on your cynicism about open hardware products. I must admit that history is full of open hardware failures, like the adorable Chumby (what went wrong?), but times have changed and I think you will find that the open hardware is building significant momentum today, I'd encourage you to take another look.

The purchase that turned me into an open hardware evangelist was the Planck EZ mechanical keyboard: https://ergodox-ez.com/pages/planck

It's a joy to use. The layers feature of the open QMK firmware blew my mind and changed how I think about typing. The keyswitches take seconds to replace so it's extremely easy to repair/maintain, which is great for the planet. It's tiny and portable, which was perfect for my needs before the pandemic hit and I stopped going outside. And perhaps most importantly, the company seems pretty successful, they seem to be a competent business that is in it for the long haul.

I am also very impressed with my Pinebook Pro: https://www.pine64.org/pinebook-pro/ The year of the Linux desktop may never come, but this shockingly cost-effective open hardware laptop convinced me to quit Apple products after a decade of loyalty. For my needs, which are mostly browsing the web, editing code, and SSH-ing into servers, it's good enough for like 1/10 of the price. I'll grant you that Pine64 is more of a hobbyist project than a business, but it seems extremely successful on its own terms and seems sustainable despite selling stuff basically at-cost.

I've now ordered a System76 Thelio desktop, also open hardware (although closer to Apple prices, performance costs money I guess). https://system76.com/desktops

I don't say all of this to suggest that Remarkable is bad, it seems pretty good. I'm just saying that it can be better on open source software and hardware, without it hurting the business or the product. It might even help.

Thanks for the link, the Github repos greatly strengthen your case that we should consider this to be using open source software.

I'd just like to say that I searched their website and wasn't able to find any link to these repos. I think that open source is something that should be touted as a feature, not something hidden in shame. Perhaps their target audience doesn't care about source code, but would it kill them to mention it somewhere?

In short, I think one factor in deciding whether a product is open source is whether it is advertised as open source (and has the repos to back that up). It's harder to get collaborators and benefit from open source if nobody knows that the source code has been published.