Quote from: thom88 on October 13, 2021, 06:44:31 PM

Do you happen to know (even if just testnet) examples of such opening and closing/settle transactions?

Take a look at this blog entry. There are multiple ways of settling the balance of a channel on-chain. Here's an example of a dual-funded channel.

Quote from: thom88 on October 13, 2021, 06:44:31 PM

Isn't there any special bitcoin script placed in those transactions? So its a simple 2of2 output?

The funding transaction output is locked with a simple 2 of 2 multisignature script. Before that transaction is broadcast by the funder, both parties sign a commitment transaction which spends that output. Commitment transactions contain more sophisticated scripts, especially when there are unsettled HTLCs.

Quote from: BlackHatCoiner on October 13, 2021, 07:00:35 PM

AFAIK, each settle transaction has an OP_RETURN sign.

OP_RETURN would make the coins unspendable. There is no reason why Lightning would use it.