Jenkins slave supported platforms?

Can Jenkins slave be installed on Mainframe? Over the years, I’ve built a DevOps solution with IBM ClearCase (has a z/OS extension) , ClearQuest and BuildForge (has an agent on z/OS) which supports Mainframe, Informatica, Unix and Windows. Now I am thinking about migrating it to the modern tool such as Jenkins to replace BF, JIRA to replace CQ and Git to replace CC. I am not sure if I can do that with the z/OS piece, need a way to submit job to mainframe and get back the result.

You certainly can. You need z/OSMF active on z/OS, might already be as it is part of z/OS. You need z/OSMF Jobs Rest activated and to make it really easy install zowe cli where jenkins runs and go. Have a look at https://zowe.org and it is shown howto at
https://medium.com/zowe/continuous-integration-for-a-mainframe-app-800657e84e96