@kisu
I am not sure how you can say that estriol will not help with Genitourinary Syndrome of Menopause (GSM).
Numerous research studies show that estriol (specifically in low-dose vaginal gel or cream form) is highly effective at treating Genitourinary Syndrome of Menopause (GSM). Plus, it is safer and less likely to cause bleeding . links below

Also the hormone amount needed depends on each individual and needs to be guided by a hormone specialist.

I am finding from self reporting that many women without a uterus/ovaries seem to need stronger intervention in the form of estradiol. Whereas, women who still have a uterus/ovaries frequently have a problem with bleeding especially if estradiol is used vaginally. My hormone doctor refuses to use estradiol vaginally, he says that it is just too dangerous. Indeed, in Europe some forms of estradiol are restricted after 2 months. https://www.medscape.com/viewarticle/919501

Estradiol is safest used as a topical systemic cream, not vaginally. Even with topical use estradiol may be too strong for many women. So be sure to have the appropriate tests and start with the smallest amount and strength.
Some forms of estradiol have been restricted to limited use in Europe. https://www.medscape.com/viewarticle/919501

Progesterone is always appropriate to use to balance estrogen use. There is a reason why the body always produces progesterone; it makes estrogen safer, and even if you don't have a uterus/ovaries you have breasts and all the other estrogen receptors found in the body. Keep yourself safe.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7188038/:,mostly%20undetectable%20throughout%20the%20study.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9452593/.
"Conclusions
Ultra-low-dose 0.005 % estriol vaginal gel is safe and effective in preventing recurrent urinary tract infections in postmenopausal women with genitourinary syndrome of menopause, reducing the incidence and potentially decreasing the susceptibility to urogenital infections by improving vaginal pH."

Estriol is also shown to maintain bone health:
https://pubmed.ncbi.nlm.nih.gov/8741364/
Hyaluronic acid suppositories are recommended by Sloan Kettering for vaginal atrophy. I personally have found a larger impact from hyaluronic suppositories than from estrogen vaginally.

I have found from talking with women about BHRT/HRT for decades that we are all individuals and need the help of a hormone specialist and some good hormone testing and even then the body decides what it wants to do with the hormones which you use. Indeed, the body has the ability to convert most hormones into other hormones. Estriol is one of the few hormones that does not convert to other hormones, which is one reason that it is so safe.

Also, one more warning, many of us continue to make our own estradiol decades into menopause. So if you then start supplementing with estradiol without hormone testing, you run the risk of too much estradiol and all the problems which comes with that. Until just recently at the age of 73 years old I have made plenty of estradiol and even at 73 I make some estradiol and am just beginning to need a small amount of estradiol systemically.

Over and over again I have seen women who decide to follow someone's advice to take estradiol vaginally and then they have to have a D&C because of hyperplasia and bleeding. Start with the least amount needed and least strength plus have a good doctor and good hormone testing. Keep yourself safe.