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![](https://discuss.tchncs.de/pictrs/image/367855b9-f175-4b68-a9c1-aeeb8c3f8319.png)
ATTiny would definitely work. Ive use them for really really long timer systems with some trial and error.
You should maybe just look at a bigger battery depending on what lifetime you would expect? They are not exactly super low power(at least the ones I have used)
Looks great!
Although I did wonder why you censored your languages and left your author names open lol.