curl -s https://versionhistory.googleapis.com/v1/chrome/platforms/mac_arm64/channels/stable/versions | plutil -extract versions.0.version raw -o - - would be more elegant but I'm figuring that macOS Monterey can't be assumed

Just came here to see if there was a PR yet for this. This was my solution:

appNewVersion=$(getJSONValue "$(curl -fsL 'https://chromiumdash.appspot.com/fetch_releases?channel=Stable&platform=Mac&num=1' )" "[0].version" )

I'm still researching an alternative, but all of the approaches suggested so far have a problem: they pick up early stable release versions. The current version returned is 121.0.6167.75 which has a 0.25% rollout. That does not match with the pkg download URL. 121.x isn't scheduled for a full stable release until the 23rd.

https://chromiumdash.appspot.com/schedule
https://chromereleases.googleblog.com/2024/01/early-stable-for-desktop.html

ok, I've reverse-engineered what https://chromeenterprise.google/browser/download/#mac-tab does, and here's my new proposal:
appNewVersion=$(getJSONValue "$(curl -fsL "https://versionhistory.googleapis.com/v1/chrome/platforms/mac/channels/stable/versions/all/releases?filter=fraction>0.1,endtime=none&order_by=version%20desc" )" "releases[0].version" )

API reference: https://developer.chrome.com/docs/web-platform/versionhistory/reference

Wow, well done!

Can someone make a final pull request with the agreed upon best solution? @fraserhess ?

my pull request can be cancelled; it looks like @fraserhess has the best solution as it is what the browser itself uses

Sorry to comment on a closed PR but it looks like
appNewVersion=$(getJSONValue "$(curl -fsL "https://versionhistory.googleapis.com/v1/chrome/platforms/mac/channels/stable/versions/all/releases?filter=fraction>0.1,endtime=none&order_by=version%20desc" )" "releases[0].version" ) might not be giving the latest stable new version.
@drtaru was kind enough to help me on this and the following filter might resolve this as it gives us the latest Chrome version.
appNewVersion=$(getJSONValue "$(curl -fsL "https://versionhistory.googleapis.com/v1/chrome/platforms/mac/channels/stable/versions/all/releases?filter=fraction>=0.1,endtime=none&order_by=version%20desc" )" "releases[0].version" )

Yes, I can see that versions do not match. Looking at Google's JS again I think the filter should be for a fraction greater than 1% instead of 10%

appNewVersion=$(getJSONValue "$(curl -fsL "https://versionhistory.googleapis.com/v1/chrome/platforms/mac/channels/stable/versions/all/releases?filter=fraction>0.01,endtime=none&order_by=version%20desc" )" "releases[0].version" )