Have you checked that Interrail actually makes financial sense for your journey?
If you haven't travelled by train in Ireland for some time, you may be surprised to learn that Irish trains are now relatively inexpensive, even if tickets are purchased on the day (as long as you do so online around two hours before travel).
First class is now only available on the Dublin-Belfast and Dublin-Cork routes, not even on all services on these routes, and on some stock the sole additional benefit of first class is a table lamp.
And, whilst they're standard class only, there's a couple of rover tickets available.
The Trekker ticket valid for 4 consecutive days comes in at €88. There's also a 5 in 15 Explorer (I think that's the name?) at €128.
You're almost certainly aware, but worth mentioning to others. Fares in Ireland were decreased by 20% in 2021 I believe and haven't risen since. I first bought one of those Trekker tickets in March 2020 and it was €110 then. When I next came to do one I thought the ticket clerk at Connolly was selling me the wrong thing at first, as I hadn't appreciated they were included in the decrease too.
Interrail is unlikely to make financial sense in Ireland, unless you're planning a fair bit of cross border travel. Neither Irish Rail nor Translink offer rover type tickets valid across the whole island, though Translink do offer day/3 day/weekly passes for Northern Ireland only, including a special Sundays only £10 day ticket for any train in NI.
I used to go over to Ireland a lot, but haven't been over much since Irish Ferries and Stena starting smashing up Holyhead Port between them. The new Stena ferry timetables are dreadful for train connections.