Mac desktop apps tried so far:

Mastonaut - Straightforward UI. Minor bugs on machines with multiple monitors. I like the experience, but can't find search in the UI.

Hyperspace Desktop - Clean UI. I like the Activity and Recommended features. But I want to see my notifications and at least one feed at the same time, and Hyperspace doesn't do that. Might be good for easily distracted people who want to focus on one timeline at a time.

IMHO, the one-feed-at-a-time approach is well suited for mobile. On the desktop, it feels confining.

I'm not finding many apps in the Mac App Store that appeal to me. Mastonaut is the best so far, and I can't find the search in its UI.

So for now the web UI will have to do. Next stop: GitHub...

Now trying TheDesk (https://thedesk.top/en/), a cross-platform desktop client for Windows, Linux, and macOS. Not as polished as Hyperspace Desktop - getting started on Mac required copying and pasting an authorization code from the browser - but it lets me see multiple feeds at once.
TheDesk - Mastodon Client for PC

Screenshot of TheDesk

One minor gripe with TheDesk is that the keyboard shortcuts are all Control key based, and I don't see a way to reassign them. For a Windows or Linux user, this won't be a problem, but I like apps on my Mac to feel like Mac apps. And I've used Emacs for literally decades, so there's some cognitive dissonance around Control key shortcuts for me.

But this is a minor gripe. I'll close my web browser and see if I can get by with just TheDesk.

I've encountered a nonfatal display bug in TheDesk. It's slightly annoying, but it doesn't keep me from using the app. I filed a bug report. Curious to see how long it takes them to acknowledge it.

As a cross-platform SW developer myself, I'm sympathetic if it takes them a while to get to it. And I'm sure every Mastodon client developer is utterly buried in support issues at the moment. I'm not holding my breath, nor am I in any way upset.