Created a content workflow model by referring default workflow model 'Request for activation' and its working fine when tested. But only issue i have observed is that publisher name is not gets reflecting in 'published' column of a page in siteadmin. Its showing publisher name as 'workflow-process-service' instead of actual user name(e.g. workflow-user-approver) who published the page through workflow.
I believe you are using a process step and choose the activation script. Instead replace the process step with Activate Page/Asset step as shown in the screenshot which has an option to replicate as participant.
Additionally if you would like to know who triggered the workflow, timeline for the page can be reviewed. Refer screenshot 2
Have an another query i.e. which configuration/permissions need to setup to hide all workflows(default) from start workflow dropdown. Once this step is done, i will enable custom workflows for specific user group.