I keep in mind OT solutions and it is possible that their functionality will be used in development of another SDKs

exactly, support for other languages (at the moment support is only for NodeJS) will be added in the near future. SDKs for Go and Python are planned first, as well as support for some UI frameworks such as React or Vue

pqb in one of the comments used the term "Sentry but serverless" which is quite accurate, but there is a plan to offer a number of other functionalities that we will not find in Sentry, e.g. collecting metrics or application logs, and all on a lightweight UI

You're right. This will be fixed and the demo URL will be available again.