Not really. See the support page regarding this:

As a new default, your phone number will no longer be visible to everyone in Signal. You can opt to display your phone number. However, people who have your number saved in their phone’s contacts will still see your phone number, regardless of your settings, since they already know it.

They know my phone number. Which in Europe is tied to me. They absolutely hold info about who talks to who

I did not yet upgrade to the latest version, but to migrate to compose I only had to copy the volume paths and the environment variables from Synology.
I can share my compose yaml by the end of the day if you need.

Before I upgrade I will try putting the cache on a SSD instead, seems it can improve performance quite a bit

The latest version of Synology with the container manager allows you to update images from the registry and will restart the container for you.
But I still migrated to docker compose to enable hw transcoding with quicksync