If say in 2020 Ukraine had stored up enough western weapons in secret, that bridge could have been destroyed
You misunderstand me.
Then, as Bobko noted, it would have been gone for the 2022 invasion
I meant two much smaller bridges, in the north of Crimea. The Armyansk Bridge and Chongar Bridge.
These two bridges are the only way to get out of Crimea and into Ukraine, because Crimea is not so much a peninsula but more an island.
Mining the area adjacent to the bridges, and blowing the bridges themselves would have effectively prevented a Russian invasion into the South of Ukraine. We would likely be using landing ships and helicopters, instead - with likely disastrous results.
There is a criminal investigation in Ukraine, in regards to why this did not happen.
So far, only one poor guy, who is essentially a nobody, is getting all the blame piled on him. He says, the invasion started so rapidly that he failed to detonate the charges that were placed around the base of the bridge pillars. That is, he was rushing, and something about the electrical wiring did not allow the charges to go off.
This does not explain why there were no mines placed along the paths of Russian potential advances.
So, more conspirologically-minded Ukrainians believe that the Southern Command was bribed by the Russians, and that these are intentional acts of sabotage.
Bottom line - Ukraine could have kept Russian forces bottled up in Crimea, with no way out, if they had spent at most $200,000 on some explosives and 1940s era mines.
Attaching below, a map where I highlighted the locations of the two bridges, and one photo of one of the bridges. You can see these are tiny bridges, that could easily have been destroyed creating impassable bottlenecks.

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