I use pair of these on my 2021 R1250GS:
https://www.aliexpress.com/item/4000138222773.html?spm=a2g0s.9042311.0.0.27424c4dNLoo4Z
I have them on extenders as I like not to see my shoulders in mirror view but their stem is the same lenght as on BMW ones.
They last about 2-3 years and then paint starts to flake. You can choose to repaint them or simply put new pair. I use them for last 10
years and my new GS is 3rd bike with them. The first pair I owned started to loose the paint after 2 years and I sanded them down and spray painted them again. But for the price they cost, it's easier to simply replace them and that's what I do now.
When I got my bike from the dealer, it had "option" alloy mirrors. Riding the bike home for the first time I was not very happy with the view on them as the showed less of the view compared to my mirrors from Aliexpress. The same day I got call from the dealer's mechanic who was rebuilding the crashed 2019 GSA he purchased and he offered half a price for the mirrors from my bike as he heard me commenting that I didn't like mirrors that much. So the deal was made and he paid me 200 euros for BMW mirrors. I sold them to him and was happy with the other mirrors and 200 euros in my pocket.