Alright so I think I figured it out but I'll post here my solution for others and open it up to additional conversation.
In a lab vcenter (7.x vcsa) and lab loginsight (8.10) environment I did the following:
This is not an exact/details list of commands/steps-- just high level what I did...
Log Insight > Management > Agents >
Selected vSphere 7.0 - vCenter (Linux) agent template and copied it
Reproduced the File Log "audit" section from the legacy "Linux - systemd" template into this new template (ie, added the /root/ directory and .bash_history sections with tag 'audit' & tag value 'bash_history'
Downloaded Log Insight Agent Version 8.10.0 rpm
Copied RPM to VCSA /tmp directory (used winscp)
Installed liagent rpm file (rpm -i filename.rpm)
That was it. Now I have all the bash_history commands of the vcsa sending to loginsight. Happy days.