If ND does take a transfer QB, that would mean five scholarship QBs on the roster for 2023. Now, it's more than possible one or two might transfer out (my guess is Angeli would have a high probability of bailing), but it also sends a bad message to the entire QB room and potentially create a very toxic environment in that area.
Both Buchner and Pyne threw well in 2021, and it's hard to get an accurate assessment on Buchner's play this year with the O-line being so bad to start the season. My guess is that Freeman and Rees might just skip the transfer portal and go with Buchner in 2023. But I'm not solid on that guess.