I expect this is simply a case of "Valve Time" on that effort. Perhaps there's a long-term path towards more "official" SteamOS on these devices, but if there's any area where HoloISO diverges technically from SteamOS in a way that's not reconcilable, that'll be problematic for offering users a "seamless upgrade".
Long-term, I think it would be slightly more harmful to Valve's efforts if more manufacturers started standardizing around HoloISO, so I expect that this might be a motivating factor to speed up their efforts to bring official SteamOS to third-party devices.
My Deck and Linux desktop regularly have shader cache updates every few days, but they're generally tiny and finish near-instantly. I've never seen the behavior here of needing to download multiple gigabytes of shaders daily (and I'm thankful for it, with the frustrating data cap I have from my ISP).