I was diagnosed as hypogonadic back in 2007 and took regular shots of testosterone cypionate for years.
I don't think it is a cure for erectile dysfunction, although it will probably bring back a strong libido. There is one effect I was not prepared for. An enzyme called aromatase converts testosterone to estradiol. I never had boobs until I was on testosterone for six months or so.
The testosterone and estradiol molecules are very similar. This simplified and easy to understand diagram shows the various ways hormones and their precursors interact and convert.
http://ceri.com/steroid.gifPsychologist Anne Vitale has made some observations that may or may not be pertinent to you.
http://www.avitale.com/TNote15Testosterone.htmAlthough rare, I am like the people she describes.
When on estrogen my dypshoria disappears and I just feel normal. I almost feel "I'm cured" of gender dysphoria. My feminized body just feels like I think it should. It's nothing special, not particularly arousing and I don't think about gender or sex very much. I'm quite comfortable on estrogen.
When I'm on testosterone I get hit pretty hard by gender dysphoria. My libido increases, but I really really don't like being male. I become very aware of women and that I am not one of them. This is not at all pleasant.
One of the benefits of testosterone is increased energy and strength. Being hypogonadic is really quite miserable, and I felt much better after starting testosterone replacement.
Whether male or female, cis or trans, we all need sex steroids to be healthy. The ratio of T to E is quite variable. Even though I run primarily on estradiol, I find I need an occasional dose of testosterone just to keep up my strength and energy.
In summary, the change may be less than you expect, and you will probably notice some health benefits. Curing erectile dysfunction is probably not one of them.
Randi