Gmail Profiles Merge

I need assistance merging two Gmail profiles in a Windows environment.

Requirements:
- Combine all emails, contacts, and calendar events from the second profile into the first profile.
- The first profile will be the primary account after the merge.

Ideal Skills and Experience:
- Experience with Google account management
- Familiarity with Gmail and Google Workspace tools
- Attention to detail to ensure no data is lost during the merge

I ran a single person consulting business for some time and used Google Business as my computer platform.
I have now closed that business down and just want to return to being a non-commercial entity.
I have 3 emails
- a bigpond.com
- a gmail.com
- a businessname.com (which is "attached" to a Google Business platform)

I essentially want to extract myself from the Google Business platform but retain my Google "membership" and return to "Joe Citizen" status because I enjoy using Google as a "platform".
I want to retain my bigpond.com address because I have had it forever and it is the email address I use as my main point of contact - especially now that I have closed my business.
So essentially I want to retain my Google history but move to a "non-commercial" Google profile,
I am NOT a computer expert and am wary of making a mistake which would result in a loss of historical data.