Ambisonic microphones brands:

Rode (1st order)

https://rode.com/en-int/microphones/360-ambisonic

Sennheiser (1st order)

https://www.sennheiser.com/en-us/catalog/products/microphones/ambeo-vr-mic/ambeo-vr-mic-507195

Soundfield (1st order)

https://www.soundfield.com/#/products/st450mk2

Audio technica

(Not an ambisonic mic perse but Immersive 8 mic array for  3D audio capture )

https://www.audio-technica.com/en-us/bp3600

Core sound (1st & second order) https://www.core-sound.com/

Reynolds (1st & second order) https://reynoldsmicrophones.com/collections/ambisonic-microphones

Mhacoustics (4th & 6th order) https://mhacoustics.com/

Soyuz microphones (1st order)

https://soyuzmicrophones.com/013-ambisonic

Voyage audio (second order)

https://voyage.audio/

Zoom (1st order)

https://zoomcorp.com/en/us/handheld-recorders/handheld-recorders/h3-vr-360-audio-recorder/

Oktava (1st order) https://www.oktava-shop.com/?language=en

Mini dsp (1st order)

https://www.minidsp.com/products/acoustic-measurement/ambimik-1

Spcmic (3rd order) https://spcmic.com/

HD audio (7th order)  https://hdaudio3d.com/

Brahma microphones (1st & second order) https://brahmamic.com/

Nevato (1st order) https://nevaton.us/vr

Zylia (3rd order) https://www.zylia.co/

Ambi-alice (1st order) https://www.instructables.com/Ambi-Alice-a-First-Order-Ambisonic-Microphone/

Here is a nice article about 1st order ambisonic mics https://share.google/zqG1PhMUrZePvVzaJ