Has any competitor copied anything from Deno?
I think it’s fair to say that work on the experimental-strip-types option in Node was inspired/energized by a desire to try to catch up with the DX improvements found in Deno for Typescript-first development that is now the norm.
I always thought Deno was more or less trying to copy the Cloudflare (edge) runtime, but decided incompatibility was a good idea. The ecosystem bifurcation was the mistake, which they came around on, but it was already too late by then.
Deno basically popularized the idea of a standalone JS runtime that primarily relies on standard Web APIs over "in-house" APIs like Node, although we can say that those standard APIs didn't exist yet when Node was created and for most of its rising period.