Seed standalone and eurorack, 3.3v vs +/-12v

hello beautiful tinkerers,

the question has been asked, but I have not found the right answer yet.

so my (standalone) synth should interface with eurorack, and here I am stuck.
(1v/oct in/out, gate in/out, maybe 2 assignable cv in/out)

-I cannot create a -10v reference voltage from the daisy power (?) to go full mutable.

-I have to create 5-6v to send 1v/oct to eurorack (I tried to create a voltage booster in falstad but failed).

-I have to deal with incoming negative voltage, because it should be able to subtract from existing settings (will this ever work?).

how did you solve this?
use step-up converters?