I haven't seen anything like that over here, SP, but they may be in some specialist garden centres!
Years ago, I used to sell concrete garden paving etc., (as well as whole motorways), when gardening was a 'new' hobby (seventies), and any enlightened manufacturer would try a new idea back then, but, these - not so far! Derbyshire Paving's 'innovation' was drystone, chopped from a normal coloured slab, and turned inside out!
I like the idea of your blocks, you can move them around, change the height etc, and seem very versatile!