Hi Spice1 and welcome.
Yes your little trees are a bit sad but not dead!
The one with green leaves has niteogen deficiency.
The tall one at the back has bad citrus wasp gall which need to be cut off and burned. Unfortunately that wont leave that plant with much branch so it probably is the end for that one.
The one with dead leaves has green stems which means the problem might be insect driven, maybe red spider mite under the leaves or aphids that sucked the life out of the leaves.
Having this variety of issues would indicate a greater problem, maybe the potting mix is too alkaline or wet.
The other thing I wonder is how much pure sunlight these plants get each day. Lemons need at least 6hrs of solid sun each day. That amount of sun will also keep insects under control.
Lemons don't need to be too wet. Your potting mix seems open enough but maybe if you are watering daily, the root zone might be lacking air.
Another thing to think about is whether you have purchased lemon trees or tried to strike from seed. What you get from seed will be anything, maybe strong rooted or weak, may flower and set fruit or not. No way to know.
When you buy a lemon tree grafted onto root stock, you know exactly what you are getting, how strong it will be and when it will flower and fruit.
I have 2 lemon and 2 satsuma trees in individual containers and I use chamomile as a companion plant in the containers. Not only does it provide protection for the lemon tree surface roots, but it also has anti-bacterial and anti-fungal benefits for the trees.
It may not solve you lemon tree problems, but you never know, it may help. Also, lemon trees like lots of nitrogen, so maybe a good idea to put a pea or bean plant into each container as well.
Any decent potting mix not el cheapo will do. Add some soaked coir at around 30% of the bulk will help keep the medium conditioned.
Old fashioned lemon trees always did well in people's backyards because the father went down the back very night to relieve himself before bed. However you wouldn't use that much in a pot plant and you certainly wouldnt put it on everyday or even weekly!