There's nostrnet.work PWA that allows You to see different browser clienta at the same time.

With the spring browser, You can do almost the same but You (at least for my case) can go easily with the cliens that need browser extension. I'm happy with it because now I can participate in highlighter without using alby or similar things

There's plebster, which I used to follow a lot of people at the same time but I don't use that feature anymore.

Snort also has a PWA.

Good luck