Chosen Solution
Can I install macOS Catalina patcher with a hard drive that is in a external bay or do I need a external hard drive or USB?
You really can’t run Catalina on this series. Its not worth the effort! Remember this series can have limited RAM (2.26GHZ - 8 GB or 2.4 GHz - 16 GB). Also you can’t run older 16 or 32 bit apps which you likely have. Lets say you had an i-series CPU for the sake of argument - Booting up your system, from which ever drive is controlled by using the Boot Manager by pressing the Option (⌥) key when you startup your system. References: How to select a different startup diskMac startup key combinations
You theoretically could run Catalina on this MacBook but I really wouldn’t advise you to. It still has a Core 2 Duo and it’s just not worth it to get Catalina on with faults when High Sierra works perfectly fine on these MacBooks. I still use High Sierra unfortunately since that’s the maximum version my iMac supports, but chances are it’s still good for the next 5 years or so.
