I'm sure it works great, but I dislike adding too many layers to my apps. I've been burned too many times by companies that have stopped supporting and moved on to something else, or disappeared, or haven't kept up with the latest iOS changes, or whatever, and I'm forced to migrate to a different solution, to let myself use these for my personal projects, where I have very limited time and energy.
Even using React Native is more than I'd normally do, but I don't see a better cross-platform option right now.
Yup, I own a Redmi 3S Prime for ~$130. It's a great value phone and doesn't lag. MIUI is extremely slick and easy to use. I persuaded four of my family members to go for Xiaomi phones and they couldn't be more happier.