Sadly my friend, as far as ground realities go, there is no feasible way for Ukraine to get back the lost territories. Russia stands to annex that land and bulk of NATO has war fatigue now, despite not even committing a single regular. The reduced support from USA leaves a big vacuum that the subsidiaries like South Korea and UK can't fulfill. Ukraine can keep on fighting for now, but going on an offensive is no longer feasible. And no, the frozen Russian funds are not accessible by Ukraine. Americans couldn't even liquidate frozen Afghani money, and this is Russia's. The economic backlash will be severe around the globe, and countries will start scrambling to move their money in and out. Contrary to the possibility of WW3 that you are entertaining, the world economy today can neither support, nor afford that. Even your current allies will rather let Russians keep the land with an ironclad guarantee. And Russians will be happy to honor that deal as long as NATO assets do not enter a demilitarized Ukraine. The war is costly for them too after all. As long as nuclear weapons are a factor, many concessions will be given. After all, none of these countries stand to lose anything if Russia takes some Ukrainian land and ends the conflict for good. If anything these countries are raring to see their pockets stop leaking out. You should have kept your nukes.