Hey, I'm currently in an ABSN program. I started in January of 2023 and graduate in May of 2024 (15 months). Any of these programs will be difficult, but everyones experience will be different. You will get out of it the effort you put in. To me, the material is never too hard, but the time it takes to learn so much in a short period of time is where the learning curve occurs. Every class requires a different method of studying. Personally, I am very happy at my school and I preferred in person learning because I like having access to my professors, the support of my classmates and having the ability to ask questions and get answers in the moment.
I wish you luck in what ever choice you choose. You can do it!