This Thule rack may be an (expensive) option.
It certainly fits well on a Haibike, Croxden of this parish has one on his Haibike and I can confirm it's a quality piece of kit.
However, it's more of a platform rack, designed for trunk bags.
There are rails on which you could hang a pannier bag, but lower support to prevent the bag swinging into the wheel might be a problem.
On the plus side, the platform will take any realistic weight.
There are trunk bags with smaller, unfolding pannier bags which probably wouldn't foul the wheel but still provide extra capacity.
https://www.thule.com/en/gb/bike-accessories/rear-bike-racks/thule-pack-n-pedal-tour-rack-_-pp_100016