If you would like to stay on macOS, buy a used MacBook (Pro). Some owners treat their MacBook (Pro) like a jewel. Even one or two years old ones can look like new. Performance-wise they are still great compared to the latest siblings.
A week ago I bought a MacBook Pro 15" (Mid 2014) with 512 GB SSD and dedicated graphics chip. I can drive two external 4K displays at 5120x2880 (looks like 2560x1440) and the internal display at 3840x2400 (looks like 1920x1200), all at 60 Hz. That is all I needed. Couldn’t be happier. Cost me 1325€. Latest MacBook Pro 15" with 512 GB SSD costs 2700€.