The Kill-a-Watt is the gold standard in this for consumers. The cheaper ones probably work fine but the Kill-A-Watt is a known brand that's trusted.
You can get a smart plug that could measure and log the data from TP-Link
Besides that, as you mentioned, you can look at the power supplies and labels of things and get a good general idea what's going on. But that can vary greatly and the numbers listed are typically the max and not average. Monitors can be anywhere from 25W to 100W. Things that list 1200w like a space heater aren't a constant 1200W. That's typically a max draw and the are more likely 600W most of the time. Things like fans or other devices with motors can have a super high starting draw and then level out. Then those items with motors draw can increase quite significantly when under load. Imagine a circular saw that's on and spinning versus when it's doing a cut. The cutting puts a load on it and then could draw 3-4x the amps
how hot do these get? I was using https://www.amazon.com/gp/product/B08LN3C7WK/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 and was getting like 45-50c temps with just around 10 amps and 1000 watts.
You probably saw the one without energy monitoring. This one has energy monitoring. And there are some other differences as well. I was also confused at first