Well we're still actively working on the One Core API. You could technically install One Core API on a perfectly valid version of XP, however I would advise you against that as it's still not stable.
By the way, I didn't "find" it, we (me, Dibya, Samuel, Peter, Barcode and others) made it.
If you are interested in the project, this is our GitHub page:
Source code:
https://github.com/Skulltrail192/One-Core-Api
Binaries:
https://github.com/Skulltrail192/One-Core-API-Binaries
In this very moment we're working on backporting Chromium to get a proper updated browser. In the meantime, you can use Roytam's modded browsers that you can find here:
http://rtfreesoft.blogspot.com/search/label/browser?m=1
They're all updated and support TLS1.3, however they're all Firefox based.
I gotta say, though, that despite we've been actively working on it for years, we've made very little progress recently as there are still tons of kernel calls that have to be backported. Its usage it's simple: there are two kernel and a modified HAL among other things. Whenever a call is valid/legacy, it goes directly to the old kernel and comes back, if however a call is new, it's either redirected to an old call which would behave the same (like GetThickCount64 which is redirected to GetThickCount) or, if it's not available in the original kernel, it's redirected to a new kernel which is made by us and it's based on both reactOS and Wine. As to the Hardware Abstraction Layer, on x86 its main thing is to allow PAE up to 64 GB of RAM just like it does on Windows Server 2003, while on x64 is basically the one from Windows Server 2003 x64 which has been modified and transplanted to make it work with XP x64. We've also managed to get compatibility with some Vista drivers and we're targeting Win7, however our biggest challenge now is to get it working on UEFI as it's 2020 and Intel will be removing BIOS compatibility from next year, but unfortunately, we're not there yet...
