He could make a once-off PRSA contribution of 40% of his 2022 income + whatever earned income he has in 2023. If I assume that he won't be paying tax at 40% in 2023 as he's retiring early in the year, then it might be more efficient just to contribute 40% of his 2022 earned income. If he has no other ongoing income post-retirement aside from the State Contributory Pension, then his income will be exempt from Income Tax. So after he retires he could withdraw 25% of the PRSA value as a tax-free lump sum and time the withdrawal of the remainder so that it doesn't exceed his tax exemption threshold in any year.
I've made a lot of assumptions in the above, which might not be true. He should get advice from an accountant and a financial broker before doing anything.