I bought one of these on Ebay, shipped from China. When I bought it, cost was about $5 or $6. But that was pre-Covid, now shipping is very slow and costs higher.
No internal battery, I plug it into a USB powerbank. On low power it draws 240 milliamps, 1.2 amps on high power.
Small powerbanks do not provide enough power. When you plug it in, it is off, push the button once and it is on high power but if your powerbank will not supply enough power, it goes off without the ability to set if for low power (the second push does that). So, the smallest powerbanks do not work
I have no clue how many lumens, but I have plenty of light for bike trails on low power setting. Flashlight type of beam, round beam. Not a low and wide beam like the better bike lights for road riding. That may be an advantage if you are going up and down on a rough trail, but the narrow beam might not work that well if you have to do very much negotiating over rough spots.
I bought it for bike touring, I almost never have a headlamp turned on for that. But there are tunnels, and evenings to the pub that might require a headlight. And I carry a power bank in my handlebar bag when touring.
Should I assume from your screen name that this is in Florida, thus flatter than a billiards table? And that it is on a fairly straight gravel trail? In that case, a wider flatter beam would be better than a flashlight beam. Is this part of a brevet or something like that?
You said forest, in that case a beam that is up higher like a flashlight beam may have some benefit, as in forests sometimes you have branches hanging down. And if your beam is low and flat, it might not light up a tree branch that you are about to ride into.