Im getting back into cycling after 10 years and have a question i am pondering.

Would you think I could benefit more from dedicated exclusive on bike training with Trainer road starting now, where i could ride however the program prescribes in a controlled environment. Or should I take 8 weeks and get in a good leg focused cycle at the gym and let my time on the bike be what it will be, I would still ride a few times a week to build mind/muscle connection and stay on the bike.
I am fine with either way of training as I love the gym as much as the bike, but Im not sure which method would benefit me more?
Im leaning toward staying on the bike almost solely, thinking that i would benefit from consistent time in the saddle, but im wondering if that thinking is correct? My other hangup with 8 weeks at the gym means i wont get in much time doing exact/specific workouts once spring hits and im outside again.
Do i try and control each aspect of the training and stay on the bike/trainer? or do i build overall strength and sort it out on the road in the spring with structured training.

I just completed my first ever ftp test, and it was pretty dismal at 198 watts, which at 183lb puts me at 2.38 w/kg. Im a 42 year old male, at 6’1” i can probably get to about 175lb by summer. I started riding again in October and managed 900 miles before heading inside. Just enjoying riding my bike again, not real structure. I know there is plenty of improvement to be made, and gains could come relatively quickly as im new to riding, but I am trying to do it as “smart” as possible. Thanks for any insight/advice.