On iOS you can enable Guided Access and restrict what one can do, for example disable touch and lock it to an app, until you enter a Code. I imagine Android will have something similar.
This obviously doesn’t protect against electronic forensics, but it does protect against just opening different apps and searching through the phone manually.
Like others have mentioned, change your provider. Prices are going down again, as there have been advancements on installing renewables. Energy prices at the end of 2024 were 30,5% cheaper than at the start of 2023 (Source. This is the case even though we are paying more for the modernization of the grid, because renewables are that much cheaper than other sources.