Yes, it does.

The float method needs some friction-less pulleys and setup that I am not sure I can assemble.

I am choosing the clear tubing method with a valve. Seems the easiest to do and can be cancelled if any problem arises. The idea is to have REAL pipes, Tee and valve in the bottom, and clear tubing is added on top. This way the tubing may not show the lowest 20% level, but I shouldn't allow it to go that low.

a thermal viewer will. i've used it to instantly see into my 2500-gallon poly tanks and the city's steel water tower.

it showed the water level thru plastic and metal, so i suspect glass too. it sees the temperature difference between the air in the tank and the water.

it even works perfectly with a cheap chinese thermal, like the AGM ASP-MICRO TM160 (https://www.agmglobalvision.com/agm-asp-micro-tm160), that i picked up on amazon for under $300

That's true! Even one of those cheap laser temperature guns might work.

P.S., I want a thermal viewer in my Christmas stocking. Very cool.

LOL
A thermal viewer

For me that is way, way more technical than I would like
Not to mention the price