The most common constraint is whether the DB as a service offerings support a given extension, since they don't support installing custom ones. Naturally choosing to support an extension across a fleet of hundreds of thousands of instances (running dozens of different minor versions) isn't a decision made lightly, so it can take a while for new extensions to be supported.
Shameless plug (StackGres team member here) but StackGres possibly has the largest selection of ready-to-use Postgres extensions [1].
Give it a quick try on any Kubernetes cluster, like k3s on your laptop (one command install), and install any extension from the Web Console or a 1-line in the SGCluster yaml.
Give it a quick try on any Kubernetes cluster, like k3s on your laptop (one command install), and install any extension from the Web Console or a 1-line in the SGCluster yaml.
[1]: https://stackgres.io/extensions/