Definitely get power of attorney. Scams are a real thing, and you need to be in a position to monitor his accounts, advocate for him, make payments on his behalf, etc.

Research if his hone state has a way to anonymously contact DMV to initiate a medical review.

Virginia has such a program and I filed against my mother. I was contacted by a medical reviewer a few days later and her license was suspended while a review was opened. Back door way to remove driving privileges.

You can always leave a message for your parent’s GP and or email any of your concerns.
Leave your contact information. This isn’t a privacy violation. I did it all the time.

Look into elder care resources in his area. Find out what’s available from adult day care, to Meals on Wheels, to visiting nurses, transportation services, social workers, case managers.

Time to establish a medical POA. Discuss having Do Not Resuscitate (DNR) order signed and POSTED (make copies for yourself).

Some communities have a program where elderly people living solo are on an “awareness program” - police/fire have a thumbnail sketch of resident (age, special needs) tied into 911 system.

If he has a presence on the Internet, make sure you get a list of all passwords.

Also, someone who is appointed to handle his financial affairs may need to get their name added to at least one account to be able to have funds to pay bills, etc. if hospitalized.

One might also check with financial institutions to see if they require particular forms to be signed ahead of time for one taking over financial affairs as we found one required nothing more than the legal form, w while another did have paper work to complete - for things to be able to go without a hitch in a crisis.

Make sure his paperwork is all in order, power of attorney, medical stuff. At some point he won’t be able to tell you where all those documents are located.

OP - Without alarming the person you need a full physical evaluation to time out anything that may be causing related symptoms. You also need to help the individual understand how getting their financial. Legal and health documents and planning done.

Understanding the persons wishes and financial position will help you know options. As noted if out of the area, finding some sort of a paid case manager might be best way to monitor the situation. Ask about an hourly rate if you would need to pay for this service until something happened if the individual has no real plan. I would also look into area services I’ve might need to use where the person resides and also close to you or other
supportive family member.

Who is the person closest to him, who is doing the day to day care?

Has there been an evaluation with a neurologist? If so, this is important. It's easier for them to hear from a doctor there is an issue and how to plan to for the future. Yes, a eldercare advocate/social worker/case manager could monitor the decline and access services as needed. Protecting against scams is really hard if the person doesn't understand there is an issue and/or is stubborn. Hopefully, the parent will willingly let you be involved and take over when needed.

How old? Does your FIL have a financial planner? They will be able to guide you on what to do.

My FIL lives alone (still works actually) but is exhibiting some sharp cognitive decline in recent months. We do not live nearby. What resources do you recommend for necessary conversations? I’m wondering - maybe an elder care advocate? My spouse and I just don’t know where to start with a reluctant LO and we are not there in person day to day. We are primarily worried right now about financial protections against scams etc. thanks. I appreciate the ideas.