Good and very well detailed plan, I'm gonna share with you some industry grade insight. You really don't need 64 devices to hit 1 million streams per month. I've been building browser based bots for streaming farming for music labels for a very long time now, and this is how it goes.
1. The bot should be set up to play each track for slightly more than 30 seconds, 45 seconds is the sweet spot. There are 86,400 seconds in 1 day, factor in the time to change tracks and some ads, you can easily get 1500 streams from one run per day, from just one PC.
2. Use undetectable browsers and profiles. From 5 profiles of 1500 streams each, you get 6000 streams per day, again from just one PC.
3. Set up 3 VMs on one PC, 5 profiles on each, you get 3 x 6000 streams = 18000 streams per day. In 30 days that makes, 540 000 streams.
You'll need only 2 PC with 32GB RAM to hit a million streams per month. Mini PCs work very fine, and are super cheap.