If you do not like the font on Lock Screen maybe you can try to change the style of the Clock to the one you like. To change style of the Clock on the Lock Screen go to Settngs app > Lock Screen > Clock style and choose the one you like most.
You can also change the font style and its size on your device. To do this, head to Settings app > Display Font size and style 😉. If that won't be satisfying to you, then we would need more people being interested in your idea to forward it to our development team.
Regarding the volume slider being blurry/frosted, this one is based on preferences, and in this case we need about 20 likes to forward the suggestion further. It's important to bear in mind that visibility of the volume slider is essential, and a blurry look could be problematic to be seen on certain backgrounds.
We've already received a suggestion regarding the volume slider, that is should be next to the volume buttons on the left side. The suggestion is currently under consideration! 😀 Also, you can use the Sound Assistant app - The app allows you to move the volume slider wherever you want :).