It's been a long time (since...?).

I have some chatting friendsfriends who like to chat.

Or if they're chatting right now, you could say, "I have some friends who are chatting."
Or "Some of my friends are chatting."

To cut straight to the conclusion, to the chase, some of them don't read the room.

What you had is technically correct, but it sounds awkward. "To cut to the chase" is a good idiom. You could also say "to be blunt."

How could I explain and persuade them.?

I'm not their Japanese teacher, and I want to be on an equal footing with them, i. If they may not bedon't accepting a piece of my advice, they wouldill get upset, and settle the score with me in a sense.

If + present tense --> then + future tense
"If it rains, then I will stay home."

Other forms of the conditional are more complex:
https://www.perfect-english-grammar.com/conditionals.html

These kinds of advice are very grueling work to do.

More natural: "It's very grueling work to give this kind of advice."

So frankly speaking, I don't want to get into an involved in a conversation like this, t. The result is all dependings on the disposition of the each person.

In most cases, it would be to the bitter endn't end well.

Based on personal experiences, it verges on impossible.

Speaking of the impossible, covid COVID-19 would never ruin,. I thought it was not a big deal, and assumed that human beings could overcome the deadliest pandemic of all time like before.

I'm not sure what you mean by "covid-19 would never ruin." Maybe leave me a comment and I could try to help?

Such as the covid - COVID-19 haves resulted in such a a grave situation.

Capitalize COVID-19 (not covid-19). It never has an article before it.

The covid - 19 would becomeCOVID-19 will become similar to the flu virus in the near future.

the same a common virus as that of flu in the near future.

By the way, the other day, I completed got the second dose of the vaccine.

I've heard that although a lot of people have gotten the second vaccine, some of them got the so -called delta virusariant.

I think it's called the "delta variant" because it's the same virus, just a different strain.

And we never keep failing to attain the target, that is of herd immunity.

We never fail to attain = we always attain
We fail to attain = we don't attain
We keep failing to attain = we never attain (even though we're trying)

I think the last one is what you meant.

As of right now, no country has ever achieved the herd immunity.

I'm not certain that we can obtain the herd immunity under, given that the Delta variant that has very strong infectivityis highly contagious.

Even though we attain 80% of80% of the population is vaccinationed, we may not obtain the/reach herd immunity.

The Japanese Pprime minister Suga declared Japan will reach at 80% vaccination rate inthat 80% of the Japanese population will be vaccinated by October.