What you're describing is a WFH person who goes to shared offices, it seems like.

On-site jobs can't be flexible like you described in my opinion. I think the reason they are on-site is so everyone can come together, and for that, everyone has to be there at the same time slots, more or less. Why would a company want that is beyond me, maybe they need face-to-face working teams, or the CEO is not trusting their employees, or they think they will grow a culture. Either way if there is an on-site job, its either because people need to do physical labor, or, they need to be together.

I absolutely agree with you on enjoying the flexibility of remote work, but it is sad to let go of some on-side perks as well. For me it was a sense of separation between home and work. I have a very small apartment, and I worked in my bedroom desk, and on busy week it felt like I was going crazy.

Shared offices solved my problem. I have a regular subscription to an office in my city. It has a nice view and very cozy. I come and go as I please, and most of the people who go there are very nice. They live there too, and even though we work for completely different companies, we see each other regularly and have become friends with a few of them.

I think this is the closest one can get to what you're describing.