Samsung Dex is half way decent with a lot of drawbacks, and funnily enough the Tablet Dex version is optimized better, probably by intention. I wouldn't hope to see it optimized to where it is really useful since they'll be loosing cash on other products, but it could be useful from time to time.

There's nothing the Miradock can fix or make better and most usb combo hubs also fail at the same, they are just cheaper. However, if your phone isn't compatible with it, it won't be of much use. If you have an older model, a compatible keyboard/mouse combo and maybe screencast if yours supports it is enough.