I think it really depends on where you live and where you go - when I first started HRT in 2017 in California, I needed a letter from a therapist as well as a physician. I had to be diagnosed with gender dysphoria and do blood work beforehand. When I restarted recently, in WA at Planned Parenthood, they use an "informed consent" model so I didn't need any evaluation or letters, they just told me about the risks and outcomes and I signed some papers. They did a hemoglobin test via finger prick and then just blood testing later down the line.

yeah I went thru planned parenthood and they operate on informed consent. cant say the same where you live