While the Core i3-8121U was nowhere to be seen back when it leaked in the Lenovo Ideapad 330, Intel has now silently added it to its ARK database. Unfortunately, other than the confirmation that this is indeed a 10nm Cannon Lake mobile CPU, we don't have any further explanation for the lack of the integrated graphics.
According to the processor database, the Core i3-8121U is a dual-core CPU with four threads, 2.2GHz base and 3.2GHz maximum turbo frequency, 4MB of cache and a 15W TDP. It supports up to 32GB of DDR4-2400 memory in dual-channel, supports Intel Optane memory, Turbo Boost 2.0, and all the usual instruction set extensions like SSE4.1, SSE4.2, AVX, AVX2, and AVX-512.
Bear in mind that the same CPU was also previously spotted in Intel's Crimson Canyon NUC and paired up with Radeon 550 mobile GPU with 2GB of GDDR5 memory, at least in the SKU that was leaked online at German WinFuture site.
We are quite sure that we will see the Core i3-8121U in plenty of other notebooks and hopefully some other 10nm parts from Intel will surface eventually.