tire pressure variance based on ambient temperature

Overthinking? Yes.

Tires pressures recommendations are based on averages, including minimum pressure when tires are cold, and higher pressure when tires are hot on a hot day. While the standard instruction is to check and inflate a cold tire, you can add a little to the recommended minimum pressure if checking on a hot day or while the tire is hot, or at 10,000 feet, or in the hot sun, etc. In other words, don't worry about slight changes. Under inflation is probably the worst thing to worry about.