Question about PocketBook Verse

You have advantages if the store you choose is a Pocketbook partner (https://pocketbook.ch/de-ch...), as the books you buy are then automatically uploaded to the Pocketbook cloud and from there end up on your e-book reader. However, you can also buy books elsewhere as long as they conform to the .epub standard (which I believe only excludes e-books from Amazon). I regularly buy e-books from shops other than my connected shop and then load them onto the e-book reader, no problem.
Since ExLibiris also seems to be a PocketBook partner, it takes a short and simple contact with PocketBook support after the purchase at Digitec so that they can customise the connected shop on the device (see e.g. https://papierlos-lesen.de/faq...).

-Basically, you can read any book from any store except Amazon on the device (more precisely: books without copy protection aka DRM, books with watermarks and books with Adobe DRM copy protection).
with watermark and books with Adobe DRM copy protection) - books from Amazon & Google also work in principle, but this is a grey area (requires the removal of copy protection, which is illegal in principle)
-Only you and nobody else can decide for you, there are different opinions; basically a colour reader has a worse black and white display + sharpness (objectively seen - subjectively the feeling is very individual), colour reader on the other hand has the advantage of... In addition, S&W readers can be used 100% without lighting during the day - colour readers can actually also be used, but what is white (light) in the S&W reader is greyish in the colour reader. Most of them are switched on by the lighting, which of course costs more battery (lighting also seems to be very advantageous for colour content)