What should be the goals of Ukraine and Russia in the war?

They already told you. Were you not paying attention?

Should Russia be able to seize land and invade a sovereign country whenever they want?

No. Good thing they’re not doing that.

Should Ukraine not be allowed to defend sovereign territory?

The Donbas and Crimea aren’t part of Ukraine.

Should Ukraine simply give up what land has been lost?

Yes.

The other option is to keep fighting for it and still give it up when they lose.