Is Vivid worth it for a MacBook?

Yes, but you pay a premium for the original. Vivid genuinely works: it's the best-known brightness app, well-reviewed by Digital Trends and iMore. It opens the brighter XDR range macOS holds in reserve on a MacBook Pro 14"/16" or Pro Display XDR. That's about 1,600 nits, system-wide, on the keys you already press. It just costs more. MacBrightness does the same core job for $5 one-time, no subscription, and both offer a free trial first. If you want the original and don't mind the higher price, Vivid earns it. If you just want it brighter on the same keys, the $5 pick nails that one job.