Yeah we used hs-opentelemetry at my last paid position. The company was an MS shop, tho so we were using ODBC to connect to MS SQL Server which doesn't have great in-process profiling. But, at least we could figure out what quer(y/ies) were running long and then we could use the MS tools to look at the plan and fiddle with that. It was also a small org, so it's not like there was a lot of internal services in one flow -- basically everything either stayed in the Web Yesod app or in the IVR app. All our profiling could have been instrumented process profiling instead of having to use otel at all.

So, I haven't seen how easy/difficult it is to actually use otel across multiple internal service calls to satisfy one external request.