LineageOs is basically android without google. You can install the google stuff if you want it, or use open source alternatives like microg. F-droid replaces Google play. It gives you access to all the open source apps that do the stuff you do.

Ubuntu touch is more of a full Linux distro that has been optimized for a phone. It works. Mostly things function, but it is limited. Not a lot of support for mobile type apps.

I've used both on a few phones. I daily use lineages. I don't think Ubuntu is ready for daily use yet. I think with lineages, you could install it get it set up in a few hours. Take a week to find apps to replace the ones your used to. And you would not really notice that your on lineageOS.

My recommendations is to just install f-droid now and start using open source apps instead of whatever you are using. Slowly eliminate all the apps from google play. Take a month to see if you can live without google. If you can, switch to lineageOS. If not, at least you learned something.