I bought the 8GB memory version of the Raspberry Pi 4 Model B that I've always wanted.
The Raspberry Pi 4 itself has been available from 2019, and so far the memory is available in a choice of 1GB / 2GB / 4GB.
The SoC for the RazPi 4 is Broadcom 2711, and the CPU is Cortex-A72. It seems that this CPU is a product that ARM has put out to the world with a lot of confidence, a high-performance core designed to compete with the Core M processor Apparently.
And to my surprise, that RazPi 4 came out with 8GB of memory. Maybe the specs are much better than a bad PC from a developer's point of view?
So I built a development environment with RazPi, and I'll leave notes how to build it.