Please stop spreading this misnomer. It's an alternative platform. It's absolutely not a wholesale replacement, and its inner workings are vastly different to Node.
Edit: Well, someone touched a nerve! Doubt me, downvoters? You need but google to find a wealth of information to support the statement. https://www.imaginarycloud.com/blog/deno-vs-node/ is the first result, and there are a litany of other articles explaining the same.
Deno as a "replacement for node" seems like a roughly accurate three word description. Neither Node nor Deno is a programming language. Both are runtimes, just like the browser. All three of them link with V8 which is the actual runtime (technically it's a JIT compiler, and only Chromium based browsers use V8 -- Firefox uses SpiderMonkey and Safari uses WebKit).
So to answer the original question, "Does Deno work for frontend?", the premise of the question is inaccurate because Deno is an environment where you can run TypeScript code. It doesn't make sense to "run Deno in the frontend" (though maybe you could come up with some wasm monstrosity enabling an approximation of it). The better question would be, "can I share (as in re-use) TypeScript code in Deno and the Frontend?" to which the answer would be mostly yes -- but you'll still likely end up needing bundlers like webpack to help with it.
I did not want to have to sift through a hefty article to get answers to the questions. Anyone can google search, but I see the points of the comments to share condensed information not just to "link" to google.
Here's what I discovered as what I presume andrew_'s reasoning for why its not a node replacement (from the article)
"Node has been under development for over a decade, which makes it more stable and battle-tested, making it the de facto standard for server-side JavaScript. Deno has only been under development for just two years and continues to be improved. Among other things, Deno is an excellent replacement for utility scripts that are usually written with bash or python."
Edit: Well, someone touched a nerve! Doubt me, downvoters? You need but google to find a wealth of information to support the statement. https://www.imaginarycloud.com/blog/deno-vs-node/ is the first result, and there are a litany of other articles explaining the same.