Thanks for the reply. I believe getting pocketbook reader to work on the (stripped down?) tolino firmware will not be successful. The "browser" always complained about the adobeID being wrong (no, it ain't! I'm not that thick-thumbed

that I couldn't type my oh-so-simple simple password!)
Solution: I came accross this (maintained?)
alternative firmware which (for me on a tolino vision 4 HD) was "a piece of cake" to install.
I've further
sideloaded "onleihe" and "pocketbook reader" and am extremely happy with that setup for my limited needs.
And that shows: my adobeID password wasn't wrong! Onleihe + Pockebook on this firmware happily accepted it straight away (or, I managed to misstype the password "password" ;-) 7 times wrong and got my spelling right because of flashing another firmware ...no way)