That's how and why I got down to 3 days a week. I went to 4 to get my next job, then down to 2 at my current job. If you can afford it and arrange it, it's fantastic.
Isn’t that just a (very) part time job at that point? Sounds like pseudo-retirement really,
so I would assume you had quite a bit of savings by the time you went to 2-day-job.
Depends on the company/salary - I'm on 10x my initial salary when I started in tech 8 years ago so if I went down to a two day work week I'd be on 4x my initial salary still. I couldn't afford this nowadays because of lifestyle creep, but it's fun to think about. If you were in Europe and found a 2 day remote role for a US based startup you could probably find a comparable salary!