I can't take Spiro, and my endo has me using Lupron as an alternative (in the USA, btw). It works very differently from Spiro, but essentially has the same outcome. Lupron halts the testes from making T. It's very expensive, which is why Spiro is the first choice. Lupron is most often used in pre-adolescent trans children to delay puberty. As a 46 yr old trans-woman, I am using it effectvely.
Also, I use finasteride. This does not do the same as either Spiro or Lupron. It blocks DHT, not T. The upside is that you will not lose the hair on your head on finasteride, but the downside is that your body hair will not thin and you may not get fat redistribution at a more moderate pace (and other changes that a T blocker will cause), until your E sufficiently inhibits your T production. My endo explained that E alone, without Spriro or Lupron, would probably stretch the changes I would see from a T blocker from 1-2 years to 3-5 years. However, he also put in a big qualifier that everyone's bodies respond differently, which is why we have our blood levels checked.
Good luck! I would suggest talking to your endo about Lupron as a Spriro alternative. Be safe 🙂