best TB5 ssd for my laptop?

It's difficult to say what the "fastest" is because such devices are expensive. Few people have them. The few that do have only one.

But generally speaking, what you want is a Thunderbolt enclosure with a very fast M.2 chip inside.

Here's one such enclosure: https://ca.macsales.com/shop/owc-express-1m2-80g

And here's an M.2 chip: https://ca.macsales.com/item/OWC/SP4P4T1AT02/

There might be other combinations that work too.

Keep in mind the super fast SSDs get really hot so an enclosure with a good cooling system would be best.

Also, when an SSD gets too hot, then the SSD's speed will be throttled to help cool it. Different SSDs will throttle differently with some dropping the speed significantly and it can take time for the SSD to recover its full speed.

I think the fastest SSDs are not worth the trouble. I would stick with an older model SSD (one or two generations older) which will be more than fast enough and will likely run cooler & be more stable & reliable.

I understand wanting to have the fastest possible if you can afford it, but fastest is not everything.

@etresoft has probably provided the best TB5 option.

Also, make sure you have frequent & regular backups of your computer and all external media (including the cloud) which contains important & unique data. When SSDs fail, they tend to fail suddenly with little or no warning signs.

why would you need a Thunderbolt-5 device when most folks are perfectly happy with more affordable devices?