I already have quite detailed GTM tags and triggers set up and created a test Stape ss container. Can I link my current gtag and other tagging to the newly created container? Is that possible and if so how can I do that? I was looking through some online videos but the option to link to container is not there and wondering if this is maybe out of date or just not possible?
You do not need to tie the containers together in any way. They work completely independently.
You can configure your tags on your web container to send data (usually via GA4 and/or Data tag - Data Client) to your server container, here is a general description of how this can be done: Sending Data From the GTM Web Container to Server Container - Stape