You could create passive check.
These checks will get a check interval for example 10m at the icinga-master node but only execute the command “passive”.
passive will return unknown in executed by icinga.
the agentless icinga instance should execute the check by itself via cron and send the result to icingaweb2 or icinga2 via passive check result api with an interval < interval above
see Best way for a secure remote "Master" instance (only view) in case of network issues on the office - #4 by moreamazingnick