Portland has been a big ADU producer.
https://accessorydwellings.org/2021/...data-for-2020/
Denver not so much, though it builds a lot of housing.
https://www.denvergov.org/files/asse...oundreport.pdf
Minneapolis is seeing very limited missing-middle growth, and as of 2019 wasn't seeing many ADUs.
https://www.minnpost.com/metro/2019/...t-working-out/
Every situation is really different. All three cities have missing-middle options other than ADUs. All are building quite a bit of housing overall. The details of ADU legislation vary tremendously, and the details of other options vary tremendously.
I've just taken a quick look so far.