I think going with that many devices run a good chance of losing “feel” for your consumption.
Right now with one SPG in either ST or TS configuration, I’m habitually within 10 bar of predicting my pressure. Oftentimes I’m right on. I’m not anything special but I strive to correlate the impact of depth, workload and pace of breathing on my consumption.
If I were to pursue the technology solutions you’re proposing, I think I’d lose my feel for how my gas consumption is going because my attention would be on devices rather than an ongoing compilation of observations and predictive analysis.
In a parallel vein, in high performance motorcycling the first thing we do is turn off all the rider aids to understand the relation between our inputs to the bike and the response we get from the engine, the suspension and chassis. Relying on all the technological aids is the surest way to discover a shortcoming in skill at the worst possible time.