HMD Global may have received plaudits for committing to three years of OS updates for its new Nokia X-series. However, the Nokia G-series and C-series have not been treated to that same level of software support, even though HMD Global has released them at the same as the Nokia X-series.
https://www.notebookcheck.net/HMD-Global-announces-three-years-of-OS-updates-for-mid-range-Nokia-devices-two-years-for-budget-handsets-and-not-necessarily-anything-for-the-Nokia-C-series.531561.0.html
Custom ROM? You've got to be kidding. They lock the bootloader for eternity, unless someone find unofficial way. Nokia basically has shot themselves in the foot.
Custom ROMS?
So any app [from a bank, some service providers, and govt apps for lockdown support] that has root detection won't work.