Sure, anything is possible without enough c4.
Whether it’s economical to do so and the risks of making a submerged navigation hazard are worthwhile is up for debate.
I suspect we’ll land in between - many of these rigs are far beyond where anyone is likely to see them and should be retained as is. The ones closer to the coast should probably be decommissioned or modified as you suggest with navigation markers.
If all you’re looking to do is nicer input switching, a KVM switch would be a better solve.
Capture cards would be more useful if you wanted to record the gaming sessions. AFAIK they will always introduce latency as they are usually designed for a situation where that is fine.