Others in the replies also mentioned Primal has a feature like this
Nostrudel ninja has this. Also planning to do it on nostr:npub1gp4xzpmluelsakjtayc4wtzj97fhj5kakqjvsannu00xkdlf4x8s0xdqyq
Discussion
It's not the same. Primal just allows to see someone's feed. Nostrudel will actually add a read-only account where you can be "logged-in" as that person and see everything read only.