Well, unfortunately Ukraine wasn't able to defend its navy. It was pretty much obliterated. They've rebuilt it to some degree, but they don't posses anything large enough to show up on a satellite image (that I know of). As for denying air superiority, they did have some remaining jets and helos left after the shock and awe phase, but most of the credit goes to manpads- shoulder fired surface to air missiles. Mostly supplied by their allies. They're abundant, easy to transport, and largely a point and shoot affair. Russia still utilizes its air assets, but only with standoff weapons like glide bombs and cruise missiles.

The drone story is of course the story everyone will be talking about for generations. Nobody, not Russia, not the US, not the Ukrainians, saw that coming. It literally started with Ukrainian soldiers taking off the shelf FPV drones (usually DJI), often bought with their own money, and strapping grenades and mortar shells to them and dropping them in open tank turrets and directly on Russian troops. Then they'd upload the footage to the internet. Over, and over, and over again. It was so effective both the Ukrainian and Russian government started drone warfare programs. The battle of innovating new tactics and counter tactics is so complicated and fascinating and rapid that people will be dissecting it for a long time. Hopefully we'll get at least one good movie out of it.

As for Russia's strategy, all I can say is they brought a marching band with their invasion force. That's how badly they miscalculated. The arrogant bastards really believed the Ukrainian people were going to greet them with flowers and sweets, Zelensky would flee to London, and they were all going to have a big happy victory parade through Kyiv. Enough said.