I brought a Chinese 52L plastic Top Box for $50NZD around 25 quid and mounted it to a KTM 1050 ADV bike. After using it loaded for a two week 3500 km trip, nothing bad happened. it was still mint at the end of the trip :) Note:- a cheap way to adapt the mounting plate to a bike if needed, can be to use a 1 cm thick plastic cutting board to make an adaptor. They're cheap as chips and very strong. They'll take a coat of satin black paint if you don't like the raw off-white look.

Cool art work on the street!

Now you need the wireless charger/phone holder that clips onto where the bmw navigation goes from aliexpress also. £25

Cool bro

Be interesting to see how it survives... The quality of some manufacturer-branded accessories has plonked down in my experience. At the same time, price has gone in the up direction. So easy to buy an expensive bike and add £6k to that with manufacturer add-ons.