I look at that Shelly stuff, it's rather fancy. I'd go for it only if it's a permanent installation. If @pony wants just one-off thing, I guess going for any of these https://www.amazon.de/s?k=smart+plug&crid=1EHBLDW76GW5W&sprefix=smart+plug%2Caps%2C94&ref=nb_sb_noss_1 which come with an app might be cheaper. Even buying just one and using it sequentially per single appliance over a couple of days could do the trick.
I have a similar one I use for checking the power usage of some electric heaters, it works well and doesn't send your data to who knows where for the app..