Ideas for wall to wall book shelving without fitted bookcases

[D20]

I’m looking for wall to wall shelving for books but not fitted bookcases. Currently we have a large Kallax unit but wanting something less deep and less fussy for the full back wall. I think I’m looking for something less basic than planks on brackets but a similar concept. Surely not everyone has built in Billy bookcases despite what Instagram is showing me?

Would you mind sharing a pic? Now I have some names of different systems I am going to go on a trawl on insta.

Ooh I like those as an option. I wonder if we could buy some nicer wood for the shelves?

This is a similar concept but I can just slot whatever wood in https://pipedreamfurniture.co.uk/product/tiered-floor-mounted-shelving-unit-industrial-pipe-style/?attribute_number-of-levels=4&attribute_to-fit-shelf-depth=22cm&gad_source=1&gad_campaignid=22921807896&gbraid=0AAAAADNOw7z6Ge-LwYj7tMWa_gCQFXmjg may be a little too industrial though.

We are looking for the same sort of thing, @D20 - our old Billys no longer work with the other furniture in the room, but we still have a lot of books.

I looked at Teebooks, but if the shelf is only part filled it'll look really odd, I think. I have been tempted by shelfbar but as yet have not bought/tested any. They claim to work with any type of wall though:
www.shelfbar.co.uk/product/bookcase-shelves/