What we've done before is just add events in our db, or even just aggregate log data to find what we want in a grafana dashboard or whatever. Much more reliable than GA with them being blocked. And often I don't need the data they add, I care more about how many clicked a button versus how many saw it, and I'm in a better position to track that than Google.
I track all money-related metrics very precisely (using ProfitWell and spreadsheets).
I wrote code for traffic source attribution and used it to find out that my money spent on super-targeted LinkedIn, Facebook and Google ads resulted in precisely $0 revenue, so I stopped advertising and the code is now rusty.
I wrote code for A/B testing (this is something you really want to have integrated with your site) using the multi-armed bandit approach and used it to find out that with low traffic of a B2B SaaS it takes months to reach conclusions. That is still sometimes used, but not a whole lot, and only because the multi-armed bandit approach with Thompson sampling is nice enough to prioritize "better" options over time, so you can leave it running safely without baby-sitting it the whole time.
Overall the problem with a B2B SaaS is that unless you are already huge, the amount of good actionable data that you can work with is small. It's much better to spend the effort on making a product that people will want to use, e.g. talk to your customers.