Energy dashboard with hydropower reservoir filling per region: https://energiedashboard.admin.ch/strom/fuellstaende-speicherseen
Same information but can select previous years: https://www.uvek-gis.admin.ch/BFE/storymaps/AP_FuellungsgradSpeicherseen/?lang=de
Current nuclear power production: https://energiedashboard.admin.ch/strom/kkw-ch