Don't assume trans has correct level. Most dipstickless Toyotas that I've serviced were a pint to quart low on fluid. Not sure if its possible for that much fluid to disappear from volatility, but since WS is the lowest bid swill, possibly a combination of the ATF cooking off and low factory fill not checked by dealer at prep since there is no dipstick.
The cold fill straw is calibrated for 104-113F. Since ATF fluid warms up quickly and moves past that temp, and is a long wait to cool back down below that temp, Toyota came out with the fancy procedure for full ATF temp level check, which is probably the youtube video many see, with the tech OSHA burn prevention vacuum pump, and the sliding measured tube length calibrated for various vehicles transmissions.
I've used OBD scanners, inline transmission temp gauges, and even IR temp guns and have had no problem getting the correct level on dipstickless transmissions.
Older 3/4 speed transmissions, with dipsticks, weren't as critical to level as the newer 6-10 speed dipstickless transmissions. And, even though most didn't know it, there is a specific temp for accurate full level mark even on the older ATF dipsticks. For example, one of my older Toyotas has an ATF dipstick calibrated for 158F-176F for the hot range. At 158F, its at the bottom of the hot range mark, and at 176F, its at the top notch. And, the range on the disptick is pretty narrow.
Sure, there is a filter. Its micron rating is nothing to brag about, and within the life of the transmission, should never clog or be excessively restrictive from debris build up. Sad, but even a cheap orange can oil filter will easily out filter it. I guess that a 100 micron coarse fiber media filter is much better than a 200-250 micron metal bug screen. But, most automotive oil filters are <30 micron rated. I'm pretty sure the simple Magnefine filter was around 35 micron which easily beats the OE pan fiber filter. The Racor LFS ATF filter is rated down to 7 micron. If you're happy with that joke of an OE filter, so be it!