For Ruby, it should be possible to use this repo - https://github.com/open-telemetry/opentelemetry-ruby to instrument
We don't have much expertise in the team on Ruby, so have not tested it out - but would be great if you can check and share what you find
SigNoz is an open-source APM. It helps developers monitor their applications & troubleshoot problems, an open-source alternative to DataDog, NewRelic, etc.