I'm not using zram at the moment, just getting rid of swap, but my current script to get a Pi ready for embedded projects is here: https://github.com/EternityForest/KaithemAutomation/blob/mas...
What has happened, I think, is that applications that only ever needed a few hundred lines of python and a few GPIO pins have happily moved to the Pico/Pico W.
But I suspect the poor OS support and terrible documentation of most competing boards means that the clone SMBs will only have made a small dent in their business.
Not that a little market diversification is a bad thing. Any competitor that can match the broad software support and documentation of the Pi boards is obviously going to be welcome.
Mind you there must have been a cost to the zeitgeist/mindshare aspect of SBCs generally; the Raspberry Pi products weren’t the only ones to become hard to find at truly low prices. The Foundation did a great job with the Pico which I would argue meets their educational goals better than say the Pi 4B, but maybe the role of the SBCs in education is forever diminished.