Minoura makes a thru axle with 5mm threads on the ends. Pretty economical.
Ortlieb also makes one with 6mm threaded ends for their TA compatible racks, but you can just thread any rack into them. The Ortlieb one is a bit more spendy.
Point being, you have more rack options.
https://ridepdw.com/collections/baskets-bags-cargo-racks/products/minoura-rear-thru-axle-for-fender-and-rack-mounting