A refund applied to the following year is treated as a Q1 estimated tax payment for the following year. If you were instead to file separately for 2022, you can split your joint estimated tax payments any way you choose, or, if you can't agree, you would split it proportionately with respect to your combined tax liabilities. Your question suggests that you want all of the credit should go to your spouse, so your spouse would simply claim all of it. You would want to address this in your separation agreement so that there were no questions come tax-filing time. See "Joint estimated tax payments" in IRS Pub 504 for additional details:
https://www.irs.gov/publications/p504#en_US_2021_publink1000175830
Of course if you file jointly for 2022, don't apply any refund to 2023 and you can each make your own estimated tax payments for 2023. In the separation agreement you would just want to indicate who would get the cash from a 2022 refund or pay a 2022 balance due.
