I recommend folks stick with the default package manager for the language they are using.

You don't need pnpm (or Yarn), choosing something esoteric ends up just being a hurdle to contribution and a time sink.

There more things that can go wrong (as with any build environment dependency) and it can - and if you use it enough, eventually will - cause problems with edge cases when the approach to package resolution is different between package managers.

This can be a particular hassle for package maintainers; as when someone else runs into the issue with a package you maintain, they will complain to you about the problem they are having.

From personal experience dealing with bug reports, pnpm is specifically a nuisance in that regard. It is not 100% compatible with npm, and neither is Yarn.

Any potential productivity gains from using Yet Another Package Manager being slightly faster at package installation get wiped out by the very first issue that crops up.

In most instances package installation is overwhelmingly constricted by network and disk speed; you'll get much more gains from a better hard drive (e.g. NVMe). If you are in a low bandwidth environment, NPM works just fine with a regular caching proxy.