Lightweight anti theft strategies. Can be combined to suit.
Thin cafe locks.
Clip helmet straps around bike and post.
For the above it’s better if you have multiple riders/helmets. Might be easy to cut through, but very inconvenient/time consuming for a theif
Take front wheel off and take it with you so bike can’t be ridden away and has to be physically carried.
Make a pile of bikes all tangled together. They’re a git to untangle. May (will) knacker paintwork.
Keep it in eyeshot
Or a big heavy lock or 2. Kind of defeats the point of a nice light bike though unfortunately.