uBlock Origin is already less effective when running in Chrome than in Firefox. For example, it can’t detect CNAME cloaking on Chrome, while it can do that in Firefox. When Chrome finally enforce manifest V3, uBlock Origin will be even more neutered in chrome due to limited number of blocking rules.
Who cares if it already exists, just make it.
Also consider the possibility when the other, more popular projects got enshittified. Now the fleeing users have an option to switch to your project. It actually happened on one of my side project. I made it because I want to try building my own version of X. It got ~2000 users, but later down the road, X got sold to a new shitty owner that waste no time to enshittify it, and my side project suddenly grow to 20,000 users overnight.