I think this is a lost cause. Other have already mentioned this, but I'll state it again. The computers themselves are the trivial part, both the hardware and the software. You can buy a budget 11- or 13-inch laptop, new for $300 or used for $100, load them with emulators of all the 1980s and 1990s machines, and have literally the same software and much better hardware than we did back then.

If you give that to them, odds are overwhelmingly (I'm guesstimating at least 99:1) that your kids might show some interest for less than 5 minutes, and them move on to their current preferred form of entertainment. You might stretch it a bit if there is a knowledgable and enthusiastic adult sitting with them all the time, but most will only continu when the adult is present. How many hours can you spare?

Back in the 1980s, we had 3 tv channels (with mostly boring adult programming), a library that we visited a few times per month, to take out 6 books per visit, a video store where we rented movies a few times per year. Even in that restrictive setting with far less competition for attention, most of the (few) children who hade home computers only used them (personal schoolyard experience) to consume (cracked) games. Nowadays, with the endless streams of highly optimised attentions sinks (all-you-can-eat video channels, adware/IAP touch screen "games"), just giving them open-ended ways to create or great creative experiences does not stand any chance.

Now maybe your children are among the very few that do have an aptitude for open-world creativity. You can probably tell with something like Lego, or paid games with some creation tools (Minecraft, Super Mario Maker). But don't be too disappointed if they show little interest or enthusiasm. It's not you, nor the hardware/software. It's the children themselves.