I made some additions to the kit, most previously mentioned. Im staying with the Timbuk2 XS Messenger Bag (549 ci, nylon) for now. Its a tight fit, but it makes me prioritize to keep it minimal.

The current contents include:
Garmin Oregon 600 GPS.
Kyocera DuraXV, 4G LTE cellphone, waterproof/shockproof...
Anker 10,000 mAh power-bank, plus cables
Ziplock1: Minimal FAK, one pair of nitrile gloves.
Ziplock2: N-99 Isolation masks & addl nitrile gloves.
Additional cash in a small pouch.
My Kindle for passing the time reading if it comes to that.
Back-up 1xAA LED flashlight.
20 length of 550 paracord
16 oz, Nalgene water bottle
5x8 spiral notebook & pen.

The FAK in the kit includes:
3ea. 2 X 3 Fabric Bandages
3ea. Fabric Finger Tip Bandages
3ea. Fabric Knuckle Bandages
5ea. 7/8 X 3 Fabric Strip Bandages
4ea. Alcohol Prep Pad
4ea. Povidone-Iodine Prep Pad
3ea. Triple Antibiotic Ointment
1ea. 4 x 4 Gauze Pad
1 ea. Generic/waterproof First Aid tape
5.5 trauma shears.

Im considering going with a smaller power-bank. The Anker 10Ks weight is not insignificant and a 3350mAh PB is available that would probably be enough for the short term this bag is intended. Thats enough for two full charges on the phone, and its much smaller and lighter in weight.

Again, its a work in progress.