Dropping a totally random session cookie? Not allowed because cookies from your domain are now blocked.

The prompts are disabled/dismissed, not the cookies. You can still use e.g. session cookies as long as you don't make it possible to connect it to other PII.

That said, I hear you regarding the tooling. If Sentry/GA/Datadog can't be used due to collecting too much PII, that makes your life as a developer much more difficult. It might even be impossible to create a generic analytics tool that avoids PII, though it's certainly possible to create custom analytics.

Fwiw, I'm based in the EU. My strategy so far has been to talk to and interview real people and rely on aggregate counters. I can see how that makes it difficult to diagnose issues that only appear for a small percentage of users.

I'm inclined to try Debian "testing" first, but if it doesn't feel right I might give Mint a go.

Seems reasonable - I'll try "testing" on my laptop and stable on the server. That'll be my summer project. I've used Ubuntu for the last 15 years and am hoping for just a minor change

I'm also considering moving to Debian from Ubuntu, both for my laptop and for my server. I feel so unsure as to what the correct option is, and I'm old enough to no longer be interested in tinkering too much ...

I don't see why you couldn't still log non-personally identifiable information (non-PII), which should still be able to identify many issues.

That said, many analytics services do log PII, thus requiring consent.