Well my little HP Spectre x2 on 1909 with conexant audio drivers from 2017 finally had the update block removed in WU last night, which I found interesting given that I definitely have affected drivers according to the known issue details, and the known issue remains at "confirmed" rather than "mitigated" or "resolved" status. And HP/MS/Synaptics have not provided a new driver (I've been checking regularly, including checking for updates in Device Manager).
Anyway I took the plunge. As a precaution, prior to downloading and installing the Feature Update to 20H2 in WU, I uninstalled my Conexant Smart HD Audio driver in Sound, Video and game Controllers in Device Manager. I checked the box to delete the files, and I did not do a reboot on completion of the uninstall as the system requested. Instead I immediately started the update process for 20H2 in WU. It took 2.5hrs, but it completed without any issue, and now it's running 20H2!
As far as my audio goes, I was worried when I saw in WU after 20H2 had loaded itself up, that under "Drivers" it showed that conexant audio drivers had failed to install. However when I looked in Device Manager the same driver (including version number) had reinstalled, and my speakers definitely do seem to be working OK. The only issue I seem to be having after the upgrade, is that the orange light on the F6 key no longer illuminates when I mute the speakers, but it does still function as a mute/unmute key OK. On completion of the update, the orange light was on and wouldn't turn off (even when speakers were unmuted), however on a further reboot after applying more updates in WU (none of them drivers), the light is now stuck on off! I'm not bothered by this, as the speakers and the key still work perfectly well.
Putting it out there in case it helps others with non-updated conexant drivers, as this process worked well for me with no glitches. It took a long time, but this machine is a bit of a gutless wonder, so...