Spyder 5.2.1 is working now on my windows machine that has Arcpro 3.0.1 installed. I did a slightly different workflow, not sure if will break things down the line but I've tested it out on several of my arcpy dependent py scripts without any issues so far.
1) Ideally have all standalone spyder / anaconda / miniconda uninstalled and folders deleted off computer
2) Installed the latest version of miniconda
3) As administrator, started Anaconda Prompt (miniconda) and ran commands -
conda create --name chosen_env_name
activate chosen_env_name
conda install -c esri arcpy
conda install spyder
4) This automatically makes a ‘Spyder (chosen_env_name)’ shortcut which as Dan states, executes the spyder-script.py and should open spyder in the right env. The shortcut can be found under ..\Start Menu\Programs\
5) Perhaps double check by going to Spyder preferences – ‘Python Interpreter’ and that default (i.e. the same as Spyder’s) is checked. Restart kernel / restart spyder if necessary.