Interesting to see everyone seemingly writing their own browser lately. Ironic to think that AI assistance, from Google itself, might be what ends up breaking their browser monopoly.
(Speaking as someone who also started writing my own long ago, and it's far from complete.)
I think the one that made the biggest news cycle splash this last month was the FastRender experiment https://github.com/wilsonzlin/fastrender from Cursor, but I've also seen some others posted this last month. Simonw's blog seems to be tracking some under the browser-challenge tag https://simonwillison.net/tags/browser-challenge/ such as one-agent-one-browser and HiWave.
(Speaking as someone who also started writing my own long ago, and it's far from complete.)