I’ve made virtually no plans for my LO if I go first. My bad, but probably not uncommon. What would happen to her?

Maybe its time to place her. If you can afford it a nice MC, if not a nice LTC that excepts medicaid.

You need to see an elder lawyer to split any assets you have other than ur monthly income of SS and any pensions u may receive. Her split goes towards her care and when almost gone you apply for Medicaid. At the point she receives Medicaid you become the Community Spouse staying in the home, get a car, and u get enough or all of the monthly income to live on. When you pass, she will get her part of ur SS and whatever assets are left from you for her care. You can have some of her asset splint go towards a prepaid funeral.
I am just giving you the jist an Elder Lawyer can go into more detail.

If you died tomorrow in your home, do you have anyone checking in on you both to know that your wife is left on her own with ALZ? How would she know what to do to contact help? How long would it take for "someone" to find out about the situation she's in?

Or, you yourself slowly developed cognitive/memory problems, or an illness... who would check on *your* welfare?

Maybe talk to a trusted neighbor or friend to make a daily call/text to you. Leave a key hidden outside your home that only this trusted neighbor knows about in case they need to get inside.

If there is no family whatsoever she would become a ward of the state if she has dementia and is incompetent in her own affairs. A court appointed Fiduciary would manage her assets and placement.