This. IBM needs an emulator you can download and play with. I've always wanted to play with AS/400 but had no access to a non-production environment so why bother learning
A long time ago, I worked at a place which was an IBM partner (for other reasons), and I went to an iSeries training session. The user interface on these things is really ugly, didn't seem like it would be 'fun' to play around with. The interesting part was probably more the programming model.
They also said there were more iSeries in Salt Lake City than the SF Bay Area, which was HP & Sun's backyard.
Unisys did make their Windows-based emulators for OS2200 and MCP freely available for download (for personal/non-commercial use) for a few years.
Sadly, they appear to have now discontinued their free "hobbyist" program, although they still sell the emulator commercially (apparently, the MCP emulator costs US$11,000 for a 5-year license – some people will spend even more than that on a "hobby", but you'd have to be pretty devoted to a hobby to do that, and I doubt many people have that much devotion to a dying mainframe OS)
Still, that's better than IBM has ever done for IBM i. Not aware there has ever been an emulator for it. There are POWER emulators (QEMU for example), but while they can run AIX and Linux, I'm not aware of any which can run IBM i. Maybe IBM has one internally, but if they do, they are very tight-lipped about it. In theory, an open source emulator such as QEMU could be enhanced to be able to run it – but IBM's licensing probably won't allow it, which is part of why nobody appears to have done so.
IBM Cloud hosts IBM i, but it is rather expensive. In a US data centre, 0.25 core of an S922, 1GB RAM, 10GB disk will cost you US$382/month. By comparison, the same hardware for bring-your-own Linux will cost you US$32/month, showing how much of that is software licensing. AIX is US$39/month – much more reasonable software charges than IBM i is. RZKH PowerBunker, the German company which runs PUB400, can't do much better than IBM, given they still have to pay IBM licensing fees. Their prices start at US$200/month, which is cheaper than IBM, but actually a much lower hardware spec (1/20th of a core rather than 1/4 of a core). For equivalent hardware, they charge (roughly) double what IBM Cloud does.
The ones I've seen don't, no. The AS/400 boxes were pretty much designed for small-to-medium-sized businesses to stick in a closet and forget about. You may be thinking of IBM mainframes, which typically require three-phase power, but can be convinced to work without it.
These days (and for quite a while), the boxes that run IBM i are the same POWER servers that can run AIX and Linux. Before the platforms consolidated, they were still POWER servers, it was just a different firmware between the "i Series" (ran OS/400) and "p Series" (ran AIX and Linux) POWER boxes.
