I have been trying to find more details about "how lightning channels" are opened but I wasn't able to find much.
The question is only related to the bitcoin blockchain and not layer2 transactions once the channels are opened. So what does a transaction do, in order to open and close a channel and how can they be distinguished from other transactions if this is even possible.

As far as I know, you need to

a) open a channel
b) close a channel (if you wish so)

Those transactions are done ON CHAIN and I wonder if there is examples that someone could/would share.