Got it. This context helps, Nic.
1. I think you should look at an email + push notif. based marketing tool that works on behavioural + in=app events data instead of an open source CRM like vtiger.
Customer.io, braze and iterable are 3 powerful tools that can solve for your use case. They are user friendly (your marketing team will find UI/UX easy), off the shelf solutions (you’ll not be putting in a lot of engg. efforts integrating these with your CDP or backend via RESTful APIs). Best part is - if your marketing team really wants to do a lot of tests on segmentation, they can easily do it by themselves within these tools.
2. I’d be concerned about the cost though. While these tools do offer custom pricing for teams with high number of users (~1 Mn or more), you can expect to pay atleast ~1k per mo for these.