Poor birds! I think if you are willing to put the time and effort into it, I would give them a chance. You can always change your mind at any time, but if they were mine, I would give them a chance. I'm sure they are uncomfortable, so once they are feeling better, they may start moving around more.
This is a long thread with some birds that were found with really awful feet. It's very long, but there are pictures spread through, may be good for you to read.
https://www.backyardchickens.com/threads/what-to-do-with-this-foot.1285351/
I would quarantine these ones for now, at least 30 days. Start working on the feet. Get them eating and drinking and hopefully stronger. Since they were in awful conditions worming would be something I would do at some point. Safeguard liquid goat wormer is usually available locally, but with Covid I know some places are out of stock. You can also get it online. You can also use Valbazen, that usually I have to order.
Here is info, with pictures to help, for any possible lice/mites:
https://the-chicken-chick.com/poultry-lice-and-mites-identification/
This is a long thread with some birds that were found with really awful feet. It's very long, but there are pictures spread through, may be good for you to read.
https://www.backyardchickens.com/threads/what-to-do-with-this-foot.1285351/
I would quarantine these ones for now, at least 30 days. Start working on the feet. Get them eating and drinking and hopefully stronger. Since they were in awful conditions worming would be something I would do at some point. Safeguard liquid goat wormer is usually available locally, but with Covid I know some places are out of stock. You can also get it online. You can also use Valbazen, that usually I have to order.
Here is info, with pictures to help, for any possible lice/mites:
https://the-chicken-chick.com/poultry-lice-and-mites-identification/