The link in the last post shows the DP-006 as a still-available product, which is impressive. It's more versatile sibling, the DP-008, which has more tracks and basic send effects for mixing and mastering, is discontinued, which is why it's surprisingly expensive on Marktplaats.
But it's literally what I called it: the 21st century version of a 4-track cassette recorder, made to record in almost exactly the same way as you'd use one of those.