My bicycle was stolen in Norwich. What are the best locks/GPS solutions to use?

Sadly I was the latest victim of bike theft in Norwich. My Specialized Sirrus black size M was stolen outside The Food Warehouse/NRG Gym, Hall Road, 17/02/26 between 5:40pm – 6:15pm. I did not get many photographs sadly of my bike having not owned it long and only having recently added a rear black pannier rack, black mudguards, frame and saddle bag as well as lights and a garmin mount.

I tried to post in the popular Norwich Reddit but moderators repeatedly removed it sadly.

I wondered what advice is recommended for future bike security.

It seems a short, strong D lock is recommended, sometimes two even.

I have heard about hiding GPS on the bike somewhere but wondered which is recommended to get.