How to help this sweet guy
A little background - My husband and I rent the house we're living in. We moved in on December 19, 2022. That morning, I got to the house early to clean a little before moving all our stuff in, and while there, this guy showed up on the porch, meowing and scratching at the door, begging to be let in. I went out and pet him and he was very friendly. At the time he was really fat and looked healthy, so I assumed he belonged to someone in the neighborhood.
As months went on, my husband and I would see him around every now and then, but we noticed he kept getting skinnier and skinnier. We named him Arnold and would always pet him when he came around. Then we didn't see him for about a year, and we were really worried about him.
He showed up again within the last few months, and we were relieved. Last night, he came to our house again, and we sat outside with him for an hour. Every time we'd open our door he'd try to get in our house. We now think he may have been abandoned by the last people who lived here, just based on how he feels so comfortable trying to get in, the way he was begging at the door on that first day, and how he seems to have lost so much weight since we first saw him.
We couldn't let him in because we have 2 cats of our own and if we just let him waltz in, I don't want to know what fight would have ensued. He is also not neutered and we didn't want to risk him spraying all over our house. We want to rescue him and get him scanned for a microchip, get him vaccinated, neutered, and find him a home (I would love to keep him but one of our cats is disabled and needs special care so adding a third cat into the mix feels a little daunting right now). My only concern is if he belongs to someone, because he is SO friendly, I don't want to accidentally steal their cat. He's very clean, other than his fur feeling almost like dusty or waxy. He doesn't look dirty at all, I didn't see any signs of injury or any real grime on him. Any advice on what I should do here?
ETA: When I went out last night to sit with him I brought a bowl of food and a bowl of water. He ate the entire bowl of food.
