How to build a 1 deep, tile-able, "chest has items" indicator system?

I came up with two fairly compact designs, one using a dropper with an item and a hopper to provide the vertical transport, the other using QC to change state of an empty dropper, and an observer&piston T flip-flop.

If you don't mind the indicator showing chest empty, as opposed to not-empty, this is a slightly compacted version of the first design:

If you also count the floor that is necessary for the repeaters, then the original design actually goes 3 blocks lower than the chest and the one in your screenshot goes 2 blocks lower. By that definition, here is a 1-wide tileable design that also goes only 2 blocks lower:

This should be buildable from the screenshot, but here is a structure file anyway: https://drive.google.com/file/d/123gRWPtf0vC_piAfk_lpsRKyTkKqPWk0

You need 2 chests, 6 solid blocks (the bottom 3 just need a solid top surface), 1 comparator, 1 redstone torch, 3 repeaters, 1 sticky piston, 1 redstone block and 1 redstone lamp.

The circuit has a delay of 6 redstone ticks or 12 game ticks. It might break temporarily when putting in and taking out items very quickly many times, but will eventually fix itself.

But maybe the redstone block on the floor level might be a problem. In that case, you could go further up instead of further down:

This should be buildable from the screenshot, but here is a structure file anyway: https://drive.google.com/file/d/1IlEusQESzrmLrylVRc5jhEIEHNIZVigQ

You need 2 chests, 8 solid blocks (the bottom 3 just need a solid top surface), 1 comparator, 2 redstone torches, 3 repeaters, 1 sticky piston, 1 redstone block and 1 redstone lamp.

The circuit has a delay of 7 redstone ticks or 14 game ticks. It might break temporarily when putting in and taking out items very quickly many times, but will eventually fix itself.

This design does not go further up and also does not power something below the floor, but the lamp is inverted:

The cauldron in that image has water in it. If there is a roof on top of this and something like redstone dust or a lamp above that, that would also get powered. But this design can actually be copied 3 blocks higher or lower and would not interfere with the other copy (if you replace the bottom stone with an upper slab).

This should be buildable from the screenshot and description, but here is a structure file anyway: https://drive.google.com/file/d/1yXX34JEkVyhWlfgrizG64e7KfKJsTpxv

You need 2 chests, 5 solid blocks (the bottom one just need a solid top surface), 2 comparators, 1 redstone torch, 1 sticky piston, 1 cauldron, 1 redstone lamp and some water, from a water bottle, water bucket or rain.

The circuit has a delay of 4 redstone ticks or 8 game ticks. It might break temporarily when putting in and taking out items very quickly many times, but will eventually fix itself.