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> But I think I'm also going to have to at least look at what the Linux ecosystem looks like these days.

I'm in a similar position (MBA 2011, still works well but feeling the pain of 4GB RAM which was the max at the time)

One of the possible benefits of going the Linux route is to run Qubes OS and have something which is genuinely secure, and compartmentalised (e.g. work I do for different clients can be properly separated)