I have worked on implementing AS9100 and ISO 9001 in my past and I was able to use an excel checklist of sorts that took the standard and turned the elements into questions that you could check off whether you had or not and list how you met that element. Are you able to provide something of this nature? The breaking down of the standard into questions made it easy for the others not versed in ISO speak to contribute.
We do not have an excel checklist for gap analysis, but we do have an online tool to help with this assessment. As you have stated it is designed to ask in a simple manner what parts of the ISO 45001:2018 requirements are already in place so that you can assess how much there is left to do.
To find this online ISO 45001 Gap Analysis Tool go to, https://advisera.com/45001academy/iso-45001-gap-analysis-tool/