First of all: i havent used sailfish nor a Sony 10 IV so take everything with a grain of salt, but:

When looking for a familiar alternative to normal android, lineage is your go to. If there is an official build for the device it will most certainly work for everything in its power.

If a banking app doesn't allow running without google services, it won't run on degoogled lineage, but that's not really lineages fault.

I used lineage for years, and though you sometimes "feel" its a custom ROM (sometimes something doesn't work on the first try but randomly on the third, and the like) I always was able to satisfy my needs in a phone.

If you rely on apps that purposely don't run on custom ROMs, and can't find an alternative, you will need a second drawer smartphone for those I fear, but I don't think this would be any better under sailfish.