However, the "Privacy First" and "No Ads" claim gets eroded pretty quickly by cookies, and requests to trackers like n.clarity.ms, google-analytics and adtrafficquality.google.

Note - I don't actually have an issue with any of those things - if you wanna monetize this service through analytics and ads, that's up to you. But it's at odds with your privacy first claims.

Personalised advertising and content, advertising and content measurement, audience research and services development Store and/or access information on a device ...

WTF? Privacy first?

https://bulkresizeimages.online/

https://resizeimage.dev/

all these tools process image just in browser and never upload images to any server.

And more tools in the kitchen

Although from first look, I can tell you that there's a lot of text on the site and it's a bit too cramped. From my perspective, tools like these should get out of the way and the UX should be self-explanatory for an image "conversion" tool. Basically, just a box to select, drag/drop images, a few user inputs such as the output quality and format. That's about it. A single line at the top explaining what the tool does (and that it is local) should be good enough.

Also, the title says "PNG to JPG converter," but the rest of the site claims it can convert to quite a lot more than just those format. You can possibly change that to, as an example, something like: "ImageConverter - Convert images between formats, locally". And you can get rid of multiple pages, turning it into a single-page with all the possible output options.

As a sidenote, I've been using Mazanoke for this: https://github.com/civilblur/mazanoke. It's not my project, just something I happened to stumble upon a while ago, but it's similar to your project and works exactly like you would want it to.

From my test, the rest of it works great. Good luck!

Personally I don't trust claims like this unless the source code is available, which doesn't seem to be the case from my browsing