Some pics of the tile too.

What is the tile? What type of grout as not all need to be sealed? What do you hope to gain by sealing the grout? All changes of plane are required to be caulk and should not be grout.

That seemed strange to me too but there’s no caulk anywhere. The tile is ceramic and glass, not sure what type the grout is. But it’s getting dirty —so if it needs to be sealed, I’d like to. How do I tell what kind it is, and how do I clean It and keep it clean?

There is no caulking because when they grout they just fill everything with grout, not many will take that extra step and put caulking where is required.

See how in all of the corners the grout is all cracked? That is because the different planes or surfaces move in different directions at different times and groit is not flexible, so it just cracks. It really needs to be removed and replaced. The cleaner "should" work, you may want to look at renting or buying a small steamer to clean the groutt. You cannot really figure out now what the grout is so seal it after cleaning worst is it will be nothing,

Thank you—that’s helpful! Is removing grout in the corners something that’s ok to DIY? I’ve done caulking before but not grout removal.

I absolutely think you can DIY, just need to get a Dremel (carefully) or a grout removal tool to scrape out the grout as much as humanly possible.

Thank you! I really appreciate the advice!!!