Hello Iva,
I think it is a good exercise to think about this framework once you start to add tags, triggers, and parameters and connect data between different tools (Amplitude, Google Ads, Linkedin Ads, Twitter Ads). I really love a post where Daniel Wolchonok shared a video about the Data Stack at Reforge (https://www.linkedin.com/feed/update/urn:li:activity:6963174688554414080/). My suggestion and what I see in other startups, centralise everything in one platform, Segment, and then send data whatever you need. Allow Google Tag Manager to be the tool for marketers and don't allow them to use Segment (I am a marketer). It is good that marketers have the freedom to set up tags and triggers for conversions and audiences but it is good that they don't have access to everything. So, I found it very simple to do it that way, Segment for everything and then connect Segment with Google Tag Manager where Google Tag Manager will allow marketers to work on the events, conversions, tracking, pixels, etc.
I hope you find this helpful. I will try to work on creating basic documentation to collect all of that information. I found really interesting for many startups at the beginning.
Cheers,