I did a full interior LED makeover and for me it is a fantastic look. Brighter and whiter.
Festoons go in the bottom door panels and rear seat base and front footwells and glove box and also in the visor mirrors.
The overheads are conventional T10s and do OK with conventional single LED facing downward as well as the side view mirror puddle lights.
Something like this is what I have in my T10 overheads and mirror puddle lights
10x T10 194 168 W5W COB LED White Car Side Wedge Lamp License Light Bulb DC 12V | eBay
Mike