The Desktop mode shows great promise but so far fails to deliver.
Watching a simple VLC video is unusable, with lots of glitches around the UI, no ability to scrub, sound doesn't work when connected via HDMI via Steam Deck Dock, using a soundbar connected via optical. The sound does work when connected via an adapter but it is glitchy in places (using the same optical soundbar, obviously an issue with Audio between the SD Dock and HDMI/Android's handling of audio). It also draws more power than the 8a can provide via wireless charging at times, meaning you will be better off using a dock/dedicated power source to keep the device charged.
The task bar often goes unresponsive, and generally the environment needs a lot of polish. Google could have just gone for a full desktop-like mode like the Steam Deck but instead chose what feels like a 'half-assed' half finished mess that just lacks real finesse and quality and is rough around the edges.
I see references to this mode from 2024 using search on this forum - after 2 years of development it's not in a remotely daily-drive usable state, and I am uncertain as to whether future improvements rely on OS updates. Ideally this should be an Apex module/app where possible, and updates should be published frequently with bug fixes.
As it stands, it's a nice-to-have feature and shows promise, but only if Google allows engineers time to refine the overall experience. If it relies on OS updates, devices like the 8/8a/pro etc will only get a few more years and then they'll be stuck with whatever state it's in at the time.
It is disappointing it is so buggy, and apps will clearly need to be designed to work for this form factor, and I just don't think that's a realistic prospect so it will always be subpar 'best effort', rather than being a seamless, polished experience.