I am not sure what you mean by security sensitive app. Something like Samsung Knox will not work after you unlock the bootloader but that's because of the assumptions it needs to make in order to promise user data integrity. It's similar to apps requiring TPM for data/disk encryption. Self signing wouldn't restore that chain of trust. Those apps breaking is working as intended, none of the financial apps I use were affected. There's option for systemless root.

Also, I know companies have used the root status as a form of DRM. That's not about user security, it's about protecting DRM security, like Widevine L1 or L3 and the android Netflix app. Financial apps haven't been an issue for me, I am running bootloader unlocked and rooted using Magisk.