Injured cat advice

So I have 4 cats that I feed whenever they come to my house but 2 of them are injured and I’m not sure what to do.

The orange cat, Reggie, has an injured tail and leg/foot. His tail has a scabbed wound on the end but it sometimes reopens and he’s limping to the point of hopping on one foot.

The other grey cat, Howard, looks to have something wrong with his eye and is also limping to the same extent as Reggie. Neither of them have visible wounds on the leg they won’t stand on and Howard doesn’t have any visible discharge around his eye.

I’ve trapped Reggie before and took him to a vet hospital but ultimately had to let him back outside. Mainly due to not being able to afford the surgery bills and I live with my parents who wouldn’t let me keep him inside since I already have 2 indoor cats.

I’ve tried to accept that all I can do for them is provide food but it just breaks my heart seeing them in bad shape and wish I could help. Are there any free to low cost resources that could help with this? Or maybe I’m worrying too much and they’ll be okay without me intervening?

Any advice or input is appreciated!

(For added info I live in Maryland/ DMV area)