I had the original Remarkable and was any early preorder on the RM2 -- so I got grandfathered in and don't have to pay a subscription, so I can't judge if it is worth it, but the device will work fine without a subscription. You lose the Dropbox/Google Drive/One Drive integration, send by email and I think some handwriting conversion.

That being said, I do love the RM2. It really feels close to writing on paper. I also use it for reference documents (manuals in pdf format). It also supports EPUB but don't do much reading -- the form factor is a bit large for me and the eBook software is not the best (though it has gotten better).

There is a bit of a community out there so I found an Apple Automation script that adds a "Print to Remarkable" option when printing to PDF. I don't know if that requires a subscription, but it is linux underneath and you if the device is connected to your computer via USB you can use scp from the command line to copy documents to and from.

As for the templates -- it is not hard to make simple ones yourself. I did purchase one of the planner templates (was about $20 or so). I don't really use it much though. It is a giant pdf (1000 pages). It starts with a year calendar, then you can tap on a month to get that month. Then you can tap on the week to get a "week at a glance" or a day to get the daily view. But the data doesn't transfer, in that if I put something on a day page it doesn't show up on the week page. I think it would be good if you need to keep a diary (e.g. timesheet, etc) but not so good for planning. I just print my week/month from Mac Calendar to PDF and send it to the RM