>Despite all that, the workflow was so good that I'd take it over github CRs in a heartbeat.
I have to agree, here, wholeheartedly. Put a bug in that would break the build? No worries, as soon as you kicked-off a CodeFlow, it would start a prod and smoke-test build for you. Everyone could also see those breaks and block the review from completing, until you fixed them in a new iteration.
You would think that, with everyone moving (or having moved) from Source Depot to VSO/Git, CodeFlow would've falled into the deprecated products pile but because it was such a worthwhile utility, teams for entire products carried it forward, rather than relying on GitHub's CRs[1].
[1] - It became more of an amalgamation between the two [Source Depot and Git-basd-VSO] but CodeFlow was your one-stop shop to view it all.