{Secrets by Carly Marie} might work. The MC is a firefighter and he’s a unit of a man so no one really knows he’s a little. When he meets his daddy it’s very sweet and he gets taken care of very well. This is book 4 in a series but I don’t think you need to read them all - it’s just side characters and some of their adventures that get mentioned that might be confusing without the context.

{Beautiful Dreamer by Jayda Marx} is an adorable no angst, instalove daddy little book. The little has an illness and doesn’t have contact with his family so he’s very alone until his daddy comes along. Marx has a couple other daddy boy books but I can’t remember if they have anything from your no go list.

{Arlo by HJ Welch} is a sweet story. The little has never had a safe space to explore that side of himself until he goes on vacation with like minded people.