Grit is not included in layer feed.
I have never seen a layer formulation that offers a level of protein higher than 16%. Not saying it doesn't exist. I've never found it locally and I won't have feed shipped to me.
I feed a homemade mix that uses fish meal for the protein source along with Purina Flock Raiser.
The Flock Raiser is 20% protein and I think that will meet your requirements. Yes, you must offer oyster shell on the side. A 50# bag of OS costs about $10 here and it would likely last you years with Seramas. I put out multiple containers to always have it "in their faces" and picking at it.
And regardless that my flock is on pasture, I have a container of granite grit for them if they need it. In the winter, it is tough to get grit naturally so it is advantageous to have it available. Again, it is very inexpensive and lasts a very long time.