How do you do that?

Settings -> General -> Software Update -> Beta Updates

It's the same on macOS and iOS, pick "macOS Sequoia Public Beta" or the corresponding release for your device. Apple still pushes security updates for those releases, and I haven't heard of any problems with the kind of minor updates that ship late in a major release's lifecycle, so I think the risk of running this way is low. This kicks the can a year or two down the road, at which point hopefully there are better workarounds.