WebSerial was just introduced in Firefox 151. It was already available for 5 years in Chromium based browser. It's so new in Firefox that even caniuse is not up-to-date: https://caniuse.com/web-serial.

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peesem an hour ago | parent [-]

interestingly, MDN web docs claims at the top of the Web Serial page (https://developer.mozilla.org/en-US/docs/Web/API/Web_Serial_...) that Chrome does not support it, even though the support table at the bottom shows that it supports all of the features (Firefox doesn't) and has for longer than Firefox

	▲	atopal 16 minutes ago \| parent [-]
		That's because Chrome on Android has a partial implementation of Web Serial. The banner on top is to get information at a glance vs the detailed breakdown of the compatibility table.