An "Ubuntu Touch" device, or a Phone with "Firefox OS", or "Maemo" (OS), might work for you, but many of the devices that support these products have been discontinued and must be purchased second hand.
You can also install the Termux app and do a lot of linux-like stuff.
Honeydue is a neat budgeting app that couples can use to co-share the family’s money- management responsibility. It allows you to connect all your accounts – Bank, Credit Card, Loans – to the app. You can tag each of these accounts as either individual or joint – so you and your partner/spouse know at a glance where you stand with “ownership”. ...