Any recommendations for tracking devices?

There are watches that have that capability. Although they can be removed most people do not take off a watch.
There are "tags or tiles" that can be placed on luggage so you know where it is. That same tag or tile could be put in or on a shoe, belt buckle, in a wallet.
All the devices all the care you take may not prevent wandering. (my Husband was an escapee several times, scary to say the least and I did all sorts of things each time and he still found a way)
I told myself that I would keep my Husband home as long as it was safe.
Safe for him for me to care for him.
Safe for me to care for him.
Safety is not just physical safety. It is mental, emotional safety as well.
Your husbands diagnosis and decline WILL effect your health as well. Given your circumstances you need to take that into consideration.
Placing your husband in Memory Care is not "giving up, not a failure" it is admitting that he needs more care than you can provide at home. (that may mean sleeping with 1 eye and 1 ear open for who knows how long)
Your husband will probably stop wandering...when something happens that will curtail his walking. That could mean a fall or his decline will reach a point where it will be more difficult for him to wander.
You need to take care of yourself. If your doctors are unaware of your husbands diagnosis PLEASE share it with them they need to know what you are going through.
2 of the hardest things to do as a caregiver:
1. ASK for help
2. Accept help.

I have a friend who has a child that wanders, and they have installed trackers in his belt, sewn into the lining of his coat and in a carved out place in the inside of his shoe under the inner sole.

I know you asked about trackers, but do you also have the door alarmed so you’d know if he left? Mum doesn’t wander, but there’s always a first time, so I have Wyze door sensors that will notify my phone if the door opens.

Don't wait to put alarms on your doors. A friend lost her beloved husband when he let himself out at night and fell into a creek over a mile from their home. Hubby may not view the alarms as a deterrent, but you will sleep better knowing this cannot happen to you. You will also know if it is time to move him to a secure facility for your sanity and his safety.

I have no experience but a quick google found what I had heard about - adult shoes with trackers in them. https://seniorsafetyadvice.com/what-are-gps-shoes/

Anything he can remove on his own won't work but I agree with Grandma1954 that a smart watch he may keep on... not sure about at nighttime as most older people were in the habit of taking them off at night for bed. If he wears pjs to bed you may think about sewing a secret pocket where a device can be hidden.

Here is a GPS tracker for Alzheimer's:
https://www.keruve.com/

Check with your local sheriff's department. In our area, they have a program where they provide one FREE and register your information to assist you if he does wonder. Below are some links with more info and where you can check to see if it is available in your area.

https://projectlifesaver.org/about-us/where-we-are/

https://www.youtube.com/watch?v=_ekq15GL21Q

https://www.wltx.com/article/news/local/street-squad/lexington/project-lifesaver-bringing-help-to-those-with-dementia-in-lexington-county-south-carolina/101-e9e8fc22-7f33-47d9-81c3-fad1f5be88ee

https://www.rcsd.net/our-programs/project-lifesaver/

i'm unsure where you're situated however we're in california and i used 'LA Found' - they provide anklets which use gps to find someone if they go missing in real time. we didn't use it in the end as my loved one went into a facility. hopefully this helps. if you're not in california you can look to see if they have something similar in your state

My Sheriff’s Dept. recommended the apple tracking devices. They come as a set of two or four, and are about the size of a silver dollar. You can hide them almost anywhere. Even in a pocket, sewn into a lining or taped onto/into a shoe or coat. You just sync it with your phone. Easy and discreet! Good luck.

From what I've heard, trying to keep a wandering dementia patient in check damages the caretaker's ability to sleep through the night.

Please get him evaluated for memory care; when you put your head on your pillow at night, you can keep your sanity if you know where he is and that there are eyes on him while you sleep.

Take care of you so that you can have some semblance of good mental and physical health.