Unfortunately I can’t confidently say that there is really any one application that is feature-parity with Substance Painter, proprietary or otherwise. However, I think the one’s already listed are excellent choices. I wanted to also mention Material Maker if you haven’t heard of it, since it’s open source as per your question.
It’s primarily a tiling material generator, much like Substance Designer is, however it does offer some Substance Painter-esque features. I haven’t used that portion of it myself, so I don’t know how similar the workflow would be to the videos but if you are looking to try a couple applications, I think these are a couple good options!