Moved back to Barcelona to launch my startup and the setup costs are killing me - i will not promote

I moved back from living in Australia for +10 years to Barcelona to launch my consumer app. On paper it made sense: Spanish citizen, Barcelona is a great city for what I am building, one big European market right there, but I didin't realise the level of bureaucracy and costs. No income since I quit my job to do this full time (data lead), so I am draining savings with no revenue for months, and every proper way to set up here costs a fortune, incluiding the autonomo costs... And apparently, to set it up pr