The fact that URL-based imports make you uncomfortable is good. Let that discomfort guide you to adopt some extra security measures to protect yourself from third-party dependency exploits
If we are using URL-based imports, the scope of security assurances are much broader: an SSL certificate doesn't say anything about whether the current owner of a domain was the owner at the time of a dependency being safe. There is no one authority who we can expect to take swift (or even slow) action to remove malicious packages from being available on the myriad hosting protocols that are accessible through an environment like Deno
What it isn't eliminating is the ability to define "local" caches. Just because you are importing everything from URLs doesn't mean that they can't all be URLs that you directly control. You don't have to use CDN-like URLs in Production, you can entirely copy and paste all the modules you need onto a server you control and URL scheme that you maintain.
There will still possibly be good uses of caching automation in Deno (once people get bored with xcopy/robocopy/cp -r/rsync scripts), but it will likely seem a return to more bower-like tools rather than necessarily full blown packager npm-like tools. (ETA: Or proxy services like GitHub Artifacts that pull an upstream source for you and rehost it on controlled URLs with some additional security checks.)
At the least it can be made a requirement for packages in the case of multiple people with publishing access that everyone uses 2fa
They don't do a great job of advertising the changes; take a look under features/zero-installs.
The common practice is to still use yarnv1 as your global yarn, just do "yarn set version berry" inside your project to use v2. 0-config can be a breaking change - though I haven't had problems in a long time.
I wish there was something like Docker Hub's automated builds in the Node world because the way NPM works right now, what comes from NPM is an unknown. The only thing you know is if you download a specific version once, you'll always get that same version again, unless it's invalidated. Otherwise, whatever the package author wants to upload and include, that's what you get and you can't know that what you're seeing in some Git commit is what's running in your application. I wish that was the state of the art.