Hasn't anybody heard of loading the new OS on an external drive and dual-booting? (hold down Option key when powering up, you get to choose which OS you boot).

Hasn't anybody heard of loading the new OS on an external drive and dual-booting? (hold down Option key when powering up, you get to choose which OS you boot). I've got a 10.15 MBP, and I'm going to cautiously investigate macOS 11 on an external SSD while retaining 10.15 on my internal drive. I can also boot 10.14 from an SD memory card to reproduce customer issues.