I have a spare non-T2 Mac that I will be using to run macOS public betas in the summer, and Windows 10 during the rest of the year. I already have a main Mac, so the need to have this spare Mac run non-beta macOS during the rest of the year is moot, whereas I will always have use for additional Windows 10 systems.
I'm aware that one of the downsides to having Windows as the only installed OS on a Mac is that as new point releases (or Security updates if on an older, but still supported macOS version) are released, that Mac's firmware is updated and that keeping only on Windows will cause me to not get those firmware updates installed.
As a workaround for this: can I grab an external SSD (of which I have a few), install Catalina on it (or Big Sur when it is released) while it is connected to this Mac and then just use that (external SSD) to boot from and run whatever macOS update that comes out and have that process update my Mac's firmware? Ideally, I'd like to use the entire internal SSD for Windows 10 if possible until it is summer and then time to repurpose it for trying out macOS Public Betas, while still regularly keeping my Mac's firmware up to date.
I'm aware that one of the downsides to having Windows as the only installed OS on a Mac is that as new point releases (or Security updates if on an older, but still supported macOS version) are released, that Mac's firmware is updated and that keeping only on Windows will cause me to not get those firmware updates installed.
As a workaround for this: can I grab an external SSD (of which I have a few), install Catalina on it (or Big Sur when it is released) while it is connected to this Mac and then just use that (external SSD) to boot from and run whatever macOS update that comes out and have that process update my Mac's firmware? Ideally, I'd like to use the entire internal SSD for Windows 10 if possible until it is summer and then time to repurpose it for trying out macOS Public Betas, while still regularly keeping my Mac's firmware up to date.
