I just learned there are a whole bunch of bitcoin ASIC manufacturers. I thought it was a thin market but:

Bitmain

MicroBT (Whatsminer)

Canaan (Avalon)

BitFury

Chain Reaction

BitDeer

Inosilicon

Auradine

Zetagig

soon: Block

...and at least 2 more in stealth mode

Bitmain probably has >90% market share.