Thank you for sharing @gay_disabled_human . I sort of sense there has been a lot of hesitation in the past about coming out, yet lo and behold, you have a fully-supportive aunt! It is great to see your aunt encourage you - to the extent of wanting to go out to get you a rainbow plush. It is very encouraging to read your post. It must have been a huge encouragement to you also to know that she is so proud of you.
I have to really acknowledge and thank you for your quote, "so moral of the story; celebrate and be grateful for the allies in your life that make it easier to exist as a queer person". It really makes me think twice about how I interact with those who identify as a queer person.
If you have time, you may want to have a look at this handbook, Coming Out. If you scroll through, there is a section on factors to consider when coming out. It may be helpful for you when you want to have a chat to your grandparents.
Once again, thank you for sharing what your aunt did for you and what it meant to you 🙂