5 companies are making 5G chips: Huawei, MediaTek, Qualcomm, Samsung, and UNISOC/Ziguang Zhanrui. Apple intends to join them one day. Almost all are made at the 7 nm foundries of TSMC and Samsung. (Large chart below)
Huawei/HiSilicon only produces for their own phones, about 1/3 of the 5G market in 2020.
MediaTek has been #2 to Qualcomm in 4G, mostly with lower-priced chips. It is sampling an advanced 5G chip in January 2020.
Qualcomm has added the mid-range 765 to the premium 800 line and is pricing aggressively.
Samsung makes 5G chips for its own phones as well as Oppo. It's investing over $10 billion to increase capacity.
UNISOC/Ziguang Zhanrui, once known as Spreadtrum, has chip samples in testing. Backed by the very well-funded Tsinghua Holdings, it has the resources to win market share.