will it be playable on browser?

yes: post it

no: don't

why? because then I can playtest it because I only play on browser

Releasing a demo makes sense when you're either looking for feedback or have something to show which would draw attention to your game. But there are no rules here, you can do whatever you want.

Wsp and you should!

If you have something playable that will resemble the final project, definitely publish it. It's the only way for players to try it out and get some attention and feedback.

My advice: post it.

I’d definitely post the demo, especially if it already shows the core mechanics and feel of the final game. Getting early feedback helps spot issues you might miss on your own, and it also builds a bit of hype around the project. Even a short playable slice can attract testers and motivate you to keep polishing things.