That being said, we need to look at how we got here, maybe what should've happened instead and what can be done to hopefully defuse and resolve this situation.
First, dangling the carrot of NATO membership, which because with George W Bush's swansong in a NATO summit in Bucharest in 2008 (and hasn't been changed by any subsequent administration) was dangerous and deliberately antagonistic to Russia. This was compounded by successive waves of expansion after the collapse of the Soviet Union, the entity NATO was supposedly created to defend against.
Second, Zelensky seems out of his depth here (geopolitically) and should've realized this. The annexation of Crimea in 2014 should've raised the alarm bells here both that embracing to the West was dangerous and because of the threat of Russia unlikely to ever happen. This means another route needs to be paved.
Third, outright refusing to take NATO membership off the negotiating table by the US (which, as noted, was never going to happen) was downright irresponsible and clueless, particularly when the US would never put troops into Ukraine and directly get into a military conflict with Russia. That alone should prompt a less hardline approach.
This brings me to the substance of the article and a model that should've been pursued by the Ukrainian government. And that is one of neutrality, probably most similar to the Swiss model. This would include:
1. A consitutional amendment against joining any military alliance;
2. A consitutional amendment for military neutrality that might include, for example, not allowing passage by any foreign military without, say, the approval of both Russia and NATO;
3. National service, say 12 months.
4. A policy of building a defensive army. That means fixed military installations, particularly on entry points into Ukraine. It also means tactical rather than strategic weapons;
5. Equipping and training armed services in insurgency. Hardened communications, access to caches of small arms in the vent of invasion and access to weapons that have shown to be devastating against an occupying force (eg portable SAMs).
6. Exercises and planning for defending Ukraine against large outside military forces. The idea here isn't necessarily to win in such a conflict but to make the cost of victory and occupation so high as to deter it from happening.
You would probably need additional steps to protect legitimate Russian economic interests, most specifically pipelines of oil and gas to the EU and deepwater port access to the Black Sea.
As for disputed regions, you may need to adopt a model similar to, say, Nortern Ireland of joint control and semi-autonomy while still being with the borders of Ukraine.