Direct, RCT is non-existent, emergent, or difficult at best.
My vote for off-topic, but close, and on point is something like this:
https://www.sciencedirect.com/science/article/pii/S001048252...
I get flow on on my underpowered, by today's standards, cheaper than an iphone, left-field linux box on a daily basis.
Having switched Android and iPhone ecosystems every 2 years since the introduction of the G1, I've yet to see a single smart phone that could produce a flow experience for me, for exactly the same reasons everybody from Bret Victor to Alan Kay disparage regularly: tapping on glass is not the path to enlightenment, unlike the flow I get on hyprland.
Long story short, the sad backstory to the point that rubenerd makes about the crackberry is this:
Danger had this nailed with the HipTop not much past Y2K. That continued with the Sidekick II. I don't know the whole story, but somewhere in those years between 2003-2007, when I had stood in the Micro Center parking lot in Palo Alto gazing at Danger's headquarters with my Sidekick in hand thinking, "what the hell happened?", Andry Rubin exited stage left from Danger and began working on what would become Android.
The rest of it is the sad, sordid history we have now. One thing's certain though, I know many people, who'd go out and buy a sidekick tomorrow if macrohard, et al would just release the damn thing from its decades old, horribly common in the US, great-thing-killed-by-corporate-acquisition prison.
The HipTop and/or Sidkick deserved a better future than being killed in a series of acquisitions that pain everyone I know who experienced the device. It was ahead of its time, transformative, and had none of the issues that I've moaned about on everything up to and including my iPhone 12 mini and Pixel 6a.