In my experience, it is quicker to test & more likely for people to player your games when you make work it work in the browser, however if you are making a 3D game or making something that could require more power to run then you need to know how to compress your game. That being said if you are making a 2D game I would recommend it as it is just better experience for testing & for people to try it out.
If you do choose web browser then I recommend looking up a short tutorial, a lot of people has left that to the very end and I have seen people upload a web browser in game with the wrong configuration which causes the game to fail.
3D example https://mataiaz.itch.io/make-me-possessed (textures etc was compressed to make it run better)
2D example https://mataiaz.itch.io/i-was-reincarnated-as-a-slime-slayer (no compression)
If you are using unity you just need to Go to File > Build Profiles > Web(under Platofrms) and hit install. You will be able to see a "Switch Platform" button, you will need to switch to that before you build your. Once build select all the files, right click and create a zip fil. Then upload it to itch.io and select "to be played in browser" then you can test your game