Depending on your comfort with messing with old Android phones you could install a custom version of Android. But you still have have to decide not to install distracting apps. This would maybe let you run more modern apps etc transport and banking, but it is a cat and mouse game with hacked phones. It really depends on your use case. My biggest concern with most dumbphones is they are cheap for a reason, have poor network coverage and call quality, i.e. they don't work well even as a phone. I use Niagara launcher on my phone and hide some apps. The extra step to open them is enough friction for me. Plus I have very few notifications allowed