Firstly, congrats! You're starting your journey out of this s***hole.
Second, no. The 190 state sponsored visa doesn't need you to have a job before hand. It is not an employer sponsored visa.
Do not make any fixed plans yet. Not even a flight. You're only at the invitation stage and there is still more to do.
The invitation is only to allow you to apply, but the approval process is subject to many other factors: Number of case officers available to look at your case, delays if any red flags (background, history, job, etc.) need more checks and verification by the DIBP, in the midst of a immigration policy change, etc. There are claims of invitees waiting for about a month for just a case officer available to look at their case.
I'm not sure about your job market, but almost all my job applications were rejected because they needed me to fly in for a face to face interview within a month or even a week of applying. You may take longer than that to get from invitation to approval.
Third, as for the moral obligation to fulfill the sponsorship: You need to spend the first two years working and living in the state that sponsored your visa.
Though general consensus that I've seen around is that this isn't mandatory or strictly enforced.
Heck, even my agent was telling me not to bother and just go anywhere I like in Australia.
BUT, when your visa expires and you wish to apply for a citizenship, depending on how p*ssy the officer who is taking your case, they can point at you not fulfilling the conditions of the sponsored visa as a justified case not to grant you citizenship!
This has happened before. A British couple was denied citizenship just because the suburb they were staying in was a few hundred meters outside the state boundaries, despite them working in the state that sponsored their visa!
Your info is wrong about this . The british couple was on a regional VISA which has a condition " postcode restrictions listed on the visa " and it is not a PR. 190 and 189 are Permanent Resident Visas with "NIL" restrictions stated in visa.