The Nokia 2.1 was announced back in late May, and it's HMD's new budget offering. With pricing starting at around $115 for an Android Go phone with a 4.000mAh battery, it sounds like a decent deal. HMD has just released the source code for the 2.1, nearly a month after it did so for the 5.1.
HMD is required to release the source code by the GPL. That would ordinarily help with custom ROM and recovery development, but since Nokia refuses to allow its bootloaders to be unlocked, this doesn't really do much good. With that said, if you're a developer and you want to check out the code, hit the source link below. Here's a link to the download (it'll begin as soon as the link is pressed).