The Raspberry Pi foundation recently (about a 18 months ago) released their own dual-core ARM chip - the RP2040 - and a corresponding dev board - the Pi Pico. The Pico dev board runs about $4 plus shipping from authorized resellers.
Within the past few weeks, they introduced a wireless version - the Pi Pico W. It's about $6 from authorized resellers, though stock is hard to find at the moment.