The only amount on the W2 is the company's contribution to my HSA. I am retired and have no income from them.
No, you do not need to report this W-2. Your previous company's contribution to your HSA is not taxable at the time of contribution. If you do not have income listed in box 1 or 16 or do not have taxes withheld reported in box 2 or 17 you do not need to report the form.
You must report this contribution. It is required to be present on Form 8889 included with your 2021 tax return.
To report this contribution without entering the W-2, in the HSA section tell TurboTax that your employer told you about other contributions, then enter the code-W amount in the box for employer and payroll contributions for 2021 not reported in box 12 of your W-2. This will cause the amount to appear as required on Form 8889 line 9 that same as it would had you entered the W-2. Do not enter this as a personal contribution.