Matt Sephton (twitter) describes how he created a portable classic Mac using an iPad Pro, the open-source Basilisk emulator, and careful configuration of macros. It's not a toy or a gimmick: the wedding of an old but well-made operating system (MacOs System 7) and new and well-made hardware (the iPad Pro) produce a strikingly productive and minimal work environment.
… the iPad Pro is more portable, reliable and capable than my real Macintosh. That's 30 years of hardware progress for you. The iPad's display in particular is a huge differentiator—it can assume so many different resolutions it should be thought of as a collection of displays rather than just a single one. Apple Pencil is very similar in feel to my Wacom ArtPad II, but with the single huge improvement that you're drawing directly on the screen. Drawing with an Apple Pencil on System 7 is every bit as good as drawing in a native iPad app.
The only downside: Basilisk must be sideloaded or run via Xcode as emulators are forbidden in the app store.