Scared and don't know how to stand up for youngest sis.

So youngest sib turns out to be a sister. And she's safely out of the house thank fuck but she's still mostly closeted largely because she's still attached to our parents and scared how they'll react. (For reference, our parents are super conservative Christians who homeschooled us all for most of our pre-college lives.) And she's started quietly transitioning, which has been making her So Happy, and she wants to pick up the pace on that? And I want her to be happy! And she also wants to start - slow-leaking information to our parents about her being queer, which... is her right, and better for them to find out from her than a third party, but...

She's been asking my opinion on when I would be comfortable with her doing that, because I am still at home with parents and Cannot Get Away, and am also at least one flavor of queer possibly more and Very Stealth and start panicking any time I can't avoid parents being bigots about topics because I both feel extremely unsafe around them and am extremely conflict-averse. Historically my default fear response has varied between freeze and fawn?

I... I had been hoping so hard that I could get out with next-youngest sis this year and we'd be financially solvent and we could live our own lives and at least be in no immediate danger of getting tossed to the street if worst came to worst on parents' reactions to us. (Oldest sis swears that could never happen but SHE tends to aggressively see the best in our parents.) But next-youngest sis had some kind of a breakdown linked to work, and got fired, and God knows when we'll get another chance to achieve escape velocity.

I'm scared, and I know youngest sis needs to live her life, but I'm scared of being in escalated danger and also scared I will flip into freeze-or-fawn mode so hard I won't stand up for her properly and I don't know how to put my foot down or establish boundaries on topics with parents even if there was no physical danger involved!

I just... how do I handle this. How do I do right by my youngest sis and also do right by me.