True, I am all for Flutter and Tauri. However websites are better for sevices since it is not likely the company will release a fully open source app or APIs for developers to build apps for the service. There are many web clients out there that are open source and allow for a good private web experience.
And even if a company does release a FOSS app, it is hard to get the company to release the app on alternative app stores like F-Droid.
Also I do not want a million apps on my phone taking up space, that could be running in the background and harvesting my data. Websites or PWA are like one-time apps you load in the browser, use and the close to discard, especially when you use your browser private mode.