In Bloomberg.com's recent video interview of Thomas Hoenig, he references "F1C" as a measure of the dollar money supply -- in context, it sounds like he's referring to M1 or maybe M2.

That's a stumper, I have no idea.
It sounds like it might be a line number in a Fed data release?

The two figures I watch are the money supply using Divisia M3, and (lately) the MCT inflation figure.

Divisia M3 is up a pretty modest 2.1% in the year to June.
centerforfinancialstability.org - Amfm data
Changes in this figure have had a history of leading where inflation goes next, rather unsurprisingly.
e.g., it spiked in April 2020, long before the inflation pop showed up. Then it was actually year-on-year negative (shrinking money supply) Dec 2022 through Feb 2024, giving a strong indication that the inflation spike was likely to end soon.

MCT inflation is up 2.06% in the year to June.
newyorkfed.org: Multivariate Core Trend Inflation

Given that the two figures match and one tends to lead the other (at least when there is a big change), I infer that things are pretty stable right now, and except for some product- or service-specific things which may crop up, a dollar will likely be pretty stable in purchasing power in the next little while. I have lowered my one-year-forward inflation expectations again. At the moment this matters because T-bills are or will soon be gradually losing their once-in-a-generation offer of a meaningful real return.

Jim