Dimmer operates light but if the single pole is off the dimmer switch doesn't operate. The problem is the single pole light switch has only one black and white wire connected inside. No other wires in box. The dimmer has two wires in box. Two blacks connected to switch and two whites married. Is this fixable without running any other wires through wall?
You need smart switches. Period.
A smart switch can handle this problem easily. Anything else will require busting up drywall and laying new cable - possibly /4 cable to the switch loop owing to needing to support both a 3-way and provide neutral. Let's sidestep that, eh?
Why would anyone wire it this way? My guess is, the now-dimmer location started out only as a place to tap power for the light, and the switch loop was meant to be the only switch.
Use a smart switch with smart 3-way capability and wireless remote
You put the smart (dimmer) switch at the current dimmer location (with neutral). The line up to the lamp becomes switched-hot and neutral. That means the switch loop to the other switch is pretty useless. That is why you need a wireless battery powered remote which matches to the smart switch. Generally these look exactly like wall switches or dimmers, but can be mounted to the wall with sticky tape.
Selecting particular models is off-topic here, so I leave it to you to find an a) smart b) dimmer that c) accepts wireless remote and d) talks to whatever WiFi scheme you are interested in. Don't buy mail order; make sure the part that touches mains power has a UL listing, CSA, ETL or other NTRL. CE is not one, and is the mark of cheap Cheese junk that you are not allowed to use in mains wiring. CCC, FCC and RoHS are also used to fool you.
Or, use a smart module in the lamp box
In this case, you can use the wiring in and out of the lamp as always-hot and neutral. That can power any wired smart switch of your choice coughInsteoncough, provided the switches can communicate with the module via powerline or wireless signaling,
So, you appear to have a "switch loop" on the single pole switch, which was fine years ago and is grandfathered, but is not current code.
That appears to be in series with your dimmer switch, from your description of the behavior.
If you want either switch to control the light (known as "3-way" switching) you will need additional wires (or more likely new cables, unless you happen to have conduit) run to support that function. You'll also have to make sure that both locations have neutral in the box for meeting the updated codes, since you will be modifying the wiring.