We both in similar lines here. (Except ofc not the numbers. My expenses are ~0.01 monthly)

Last couple months I quit using bank accounts. Instead started using cash for all expenses. Income/Savings all-in sats. Sell sats weekly for cash.

Don't use credit card, contemplating to get one. But in 2 minds about it as I lose out on the privacy of cash.

I like your formula for Living Expenses!