I've had good luck with pail pumps for transmission/transfercase oil and differential gear oil. Never had leaks around the lid

Maybe try a different brand? I don't even remember what brand mine are. How does water and dirt get in? Never had a problem with that either, granted I keep mine under a carport so not directly in the rain.
The pump lid just sits on top of the pail, so there's no seal.
I knocked one over a while back at a shop. Was in a bad spot and my hose pulled against it. Was filling one of their lube tanks... thick arctic rated 2" hose.
Was maybe 2 gallons in the pail. Cleaning cold gear oil off a rough concrete floor was FUN!
With the pump in the center, it makes the handle no longer work well, generally leans the pail when carrying it, so then oil pours if it's fairly full.. and nevermind it sealing if the pail tips over.
It's not sealed, so water and dirt get in as well.
The Lincoln style pumps I think.are pretty well sealed, but at $1200, that simply isn't happening.
I tried a "Lumax" pump that claimed to lock into the factory lid, but it was false advertising, in no way, shape, or form does it lock to a lid. Shame.
It's mostly for topping off a few pieces of equipment that pouring from the pail is difficult. Like my Bobcat needs funnels held in place so it's almost a 2 man job. And still usually makes a mess as the funnel empties slowly and hard to judge while holding a ~40lb pail shoulder high or while trying to balance on a tire.
Might just try using a fuel jug, have extras I could donate to the cause.
McNaught make a cordless setup, but it's ~$500.
Even gave thought to building a setup with an M18 pump, but still would have $300+ into it.