@Aliyah1 ,
As I understand it, a user submits an approval request. They enter the names of the approvers in a multi-choice person field (called Dept HR Liaisons).
Each approver has to approve the request and the approval buttons should only become visible if the current app user exists in a multi-choice person field (which I now remember we already solved in a different post).
When a approver has approved a request, a multi-line text field is updated with the word "Approved". When another approver approves a request, the same field is appended with "Approved"
You then want to check if the number of people in the Dept HR Liaisons field is equal to the number of times "Approved" appears in the multi-line field. If the count of both are the same, then the single select Department Head People field should be visible.

Notice only items 2 and 3 have Department Heads, because the count of "Approved" is equal the number of approvers.
This is possible. But I must caveat it would make more sense to track the approvals in a separate SharePoint list, with a new line per approver and response.
Anyway, try the Solution below:
Add a Label into your screen and in the Text property, enter:
LookUp(
'Your Data',
ID = 'Your Unique ID',
Concat(
'Your People Column',
ThisRecord.Email & ","
)
)
Add another Label into your screen and in the Text property, enter:
LookUp(
'Your Data',
ID = 'Your Unique ID',
'Your Multi-line text column'
)
Add another Label and apply to the below to the Text property. You can of course use the same expression for anything else you need, such as whether the Buttons should be visible:
Value(//Count people in HR Liaisons field
CountRows(
Filter(
Split(
'Your Approvers Label'.Text,
","
),
Value <> ""
)
)
) = Value(//Count occurrences of the word "Approved"
CountIf(
Split(
'Your Responses Label'.Text,
","
),
"Approved" in Value
)
) && LookUp(
'Your Data',
ID = 'Your Unique ID',
'Department Head'.Email = User().Email
)
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Imran-Ami Khan