The Smurfiest Wizard Ever!
I like this concept. But count me among those who think the wizard is wonky and needs a boost. The class is balanced around spells, including spell levels, and those are essentially class features. By not advancing that part, I feel like you've thrown out the class balance relative to what other classes are getting because those other classes happen to name new abilities something different rather than a feature which says "new spell level available". And no, signature spell doesn't make up for it. That's a fun little add-on, but it's not a core feature for wizards. Wizards have lots of spell slots - they really don't use all their second level slots at high levels anyway, so it's not like treating those as cantrips is a meaingful difference. Their high level abilities are high level spells, and the class is built around that concept as if they were class features with special names.
Here's what I am currently thinking for 2nd level:
Another option I am considering (but hesitate to use) is allowing more attunement slots maybe? I am not a fan of Artificers and won't make them for this system (sorry to people who like them...). So, giving wizards more attunement slots might work.
I have also considered allow them to get their new spell levels on the even levels instead of the odd levels. Or giving them more spells slots. I don't know, nothing I can think of really screams WIZARD to me...
Or, what about allowing Wizards to use an attunement slot for "holding" a concentration spell or something?