Conditional formatting based on numeric value stored as text

I have a large workbook with many cells that contain zeros formatted as text.
I'd like to make the zero value gray so the non-zero values stand out better.

Conditional formatting does not seem to work in this case.
I'm using Microsoft® Excel® for Microsoft 365 MSO (16.0.14326.20702) 32-bit with Windows 10

I'm trying to apply the conditional formatting to the entire sheet.
I select all, then use the conditional formatting dialog to create a rule "Format only cells that contain"
"Cell value equal to"
I set a gray text as the format.

I've tried these values for the cell value equal to:

I enter the character 0, which results in a rule with =0 in the "equal to" field
I enter the string '0 which results in a rule with ="'0" in the "equal to" field
I enter the string "0" which results in a rule with =""0"" in the "equal to" field
I enter the string '0' which results in a rule with ="'0'" in the "equal to" field

None of these have any effect on the text in the sheet. The color of the text in cells containing the text 0 are unchanged from the default black.

What is the proper way to match the text value of 0 for conditional formatting?

If you're wanting to format just those cells that have a 0 as text, you can try this formula in Conditional Formatting:
=A1=TEXT(A1,"0")