I'm using Jolokia (JMX) for a log time with vanilla metricbeat, now migrating to elastic agent I can't find the Jolokia on Kibana, in Fleet menu. (Jolokia Input | Documentation)
I hope you are already using the 8.13 or the higher version of the stack. The Jolokia input is currently in beta. You have to enable Display beta integrations setting in the integrations Kibana UI.