Seems to test something different from 15 minute games.
The Elo on sites depends on the player base lots and lots.
The AI on lichess sometimes makes clearly worse moves than the ones I made. There is also room for much more in depth analysis like drop, fork, defensiveness, etc. I switched from chess to Anki and Amphetype because, while not nearly as fun, they also taught me a skill. I will get back to chess when I find an affordable automatic board. Cognitive tracking is often discussed on reddit or the QS forums.
Exist a few papers on the subject of chess as a test of cognition.
"Using within-player comparisons, we find a statistically and economically significant decrease in performance when competing online compared to competing offline." Steffen Künn 2020
DB RCT Coffee causes "more reflective decision making processes. When not under time pressure," Franke 2017
I have something similar. Have you worked outside?
I use Bitesnap and MFP to avoid most of your problems with diet tracking. Measuring exact weight of each ingredient in something I cook is still a hassle. For heart rate I recommend uECG. Many tools are being developed to track exercise in great depth such as mbientlabs' wearable accelerometry and computer vision pose estimation.
Even if user gets good time saving equipment the daily time expenditure is still non trivial. The benefits could however be great! The current biggest problem is that no automated analysis software yet exists. For more see the Kialo debate:
Less wrong deck exists now though it seems incomplete missing things like Inferential Distance.