Focus LCDs

We do not offer any off the shelf intrinsicly safe LCDs. We can custom build the LCD to supply the voltage/current requirements you need, but we are not certified as intrinsicly safe.

The lowest power displays are ones where there is no backlight. These would be monochrome character, graphic and segment displays.
Higher power displays would include TFT and OLED

Capacitive touch panel. The resistive touchscreen has a small film that might block up to 5% of the light shining through. Although resistive is less expensive and easier to integrate.

The one time tooling (NRE) to increase the brightness of a TFT runs about $1K to $2K dollars depending on the brightness and size of the module.

Yes, it is possible to have an SPI interface

the lowest cost segment option is a 4:1, but requires many more I/Os than a 4:1.
A SPI requires a chip to be added to the LCD increasing the cost and the over all size of the glass.

Static drive means that each segment is on 100% of the time or off 100% of the time. There is no duty cycle or refresh.
Dynamic means that the segment is 'refreshed' . it will not have as sharp of contrast as static drive, but requires far less pins.

There is no set number that should be exceeded. The more segments, the more I/Os required to drive them. Part of the design question is what type of interface? Spi? I2C, 4:1 multiplex, static drive? Static drive will give a really good contrast, but cannot support to many pins due to the number of l...

Nope, EL and LED are not interchangable.

The widest viewing angle LCD technology would be the UWVD. It comes with a LED backlight that can be adjusted if the LCD is built for the purpose.

https://focuslcds.com/uwvd/

There are four viewing angles. This is the direction that people will look at it. 6:00, also called bottom view, is the most popular. It means that people will be reading the display from below the display and looking up to it. 12:00 or top view is the next most popular. 3:00 and 9:00 are possible b...