I think there are two steps to this exercise. In identifying what your 'ideal' parenting would have looked like, you are identifying the actions/qualities that you value, that were withheld from you.
Then, the next step is to understand how you might still be searching for those things in your current life, and to find ways to give them to yourself.
If I had one wish for my mother, one thing that was missing - it was that I believe she was afraid of me. I wish she would have been able to invest in me and not be afraid to get involved. Now, that's never going to change. The past is the past. But, even now, I walk through life with an assumption that I'm difficult, and I'm alone with my problems because of it.
So, part of the work I need to do is change that core belief - the thought that says, 'I'm a problem and I can't be fixed'. The way to dismantle that is through a few different angles. It's in processing the past, but also, in seeing how I can treat myself differently. Something that became a coping mechanism of mine was to flat-out never engage with my own inner struggles. In a way, I became afraid of myself, just like she was afraid of me.
Now, I can try and engage with myself, instead of avoiding or ignoring or stuffing those things down.
In Gestalt therapy, it's called 're-parenting'. I don't like the term, or the classic way it's used in that technique. But, as a looser concept, I do understand it. I think it's not as applicable for people who develop different and more complex issues with their family of origin in their adult lives. But, for people who had their parenting dynamic pretty much set up at childhood, and it never really changed as they transitioned into adulthood, this exercise can be very useful.
It doesn't have to do with re-writing history, only with identifying early wants and needs that weren't met, so you can work on addressing how to have them met in your present life. And it doesn't erase what your childhood was or who that parent was. If nothing else, you can learn some empathy for yourself from identifying what you weren't supported with, back then (if that makes sense).