No personal experience with this but from what I can find Redis is not a supported technology but you may be able to place some custom sensors to capture the calls in some cases (I see no references to this being done successfully - just in theory though). Someone has created a plugin to get some metrics from Redis though:
Here is an existing RFE: https://answers.dynatrace.com/idea/146895/monitori...
I also see that Hazelcast is not a supported framework and so PurePath stitching also will not work.
Both of the above were obtained from older resources but I see no changes since then.
I'll also note that it doesn't seem like it is always enabled out of the box but for Dynatrace SaaS and Managed it appears support for Redis monitoring can be enabled if you'd like to investigate that route.