It is a dead end approach -- CRT tube factories have shut down and will not be spooled up again. And so we have no hardware to prototype these DIY hibrids. Quantum dots with tubes would have been a fun idea, but without any factories to help (unless there many hundreds of millions of dollars) -- sadly, not possible to build.
My Alternative Approach: Software-Based CRT Beam Simulators
For CRT simulation, my approach is simply to use brute refresh rate, combined with software-based electron beam simulators.
Such as 1000fps 1000Hz OLED, with 16 digital refresh cycles to emulate 1 analog refresh cycle. It's like a phosphor fadebehind rolling scan, like one frame of a high speed video of CRT. Done realtime, it temporally looks like the original CRT.
I'm also working with
Retrotink 4K to add BFI injection with a box-in-middle approach, so even though that's only 2:1 to 4:1 usually, and not beam simulation yet, this is a more futureproof approach.
There's already accolades on beginning to do CRT simulation using BFI injection, and someday, BFI injection will be electron-beam-simulators (once we have a large ratio of input:output refresh rate, to allow such fine-granularity CRT emulation).
So getting closer to a CRT tube can also be done via box-in-middle injection systems, given brute output Hz far greater than input Hz.
A more generic approach that works on more display and display technologies. The better the color gamut and HDR (for nit boosting) is, and the more Hz, the closer to CRT you can get.
Eventually, at some point in the future, box-in-middle approaches will achieve the
CRT beam simulator approach (similar to Retroarch BFIv3 suggestion). This will probably look good on 8:1 ratios, e.g. upcoming 480 Hz OLEDs in the mid 2020s decade, simulating a 60Hz CRT tube via an 8-cadence phosphor-fadebehind rolling scan algorithm with edge-blending algorithm to prevent tearing.