In Islam, a man should groom himself and look nice for his wife.
It is related from Imam Rida (A): "The women of Bani Israel deviated from the path of chastity because their men were not bothered about cleanliness and looking nice." The Imam then added: "What you expect of your wife, she expects the same from you."
It is also related that Allah is beautiful and loves beauty, and loves to see the signs of His blessings on His servants.
The Prophet (S) used to give attention to looking appropriate and presentable. Here are some narrations on some of his grooming habits, including combing and oiling his hair and beard: https://www.al-islam.org/sunan-nabi-sayyid-muhammad-husayn-tabatabai/cha...
Of course, different people have different levels of motivation and interest in these things, and different understandings of what it means to be tidy.
So yes, you can ask, and yes he should make some efforts. Even if it were not emphasized in Islam, it is still good to try to accomodate one's spouse's requests as long as they are ethical and doable. However, it is difficult to force someone to change.
Perhaps you can encourage him, if you have not already, by giving him some nice beard oil. There are also some websites dedicated to beards and men who are proud of their beards. After all, a beard is a symbol of a manly man (for men who can grow them, of course) and so it is nice if he takes pride in it.
Also since the beard is symbolic of Islam, it is nice to look after one's beard because it is part of the public image of Islam.
