Jump Rope - Instinct Standard

You do not need a separate activity for rope jumping, use one of available activities (Cardio, HIIT, Strength), and if necessary for some reason, create a workout where you can add the Jump Rope exercise.

And where can I do this so that it keeps track of how many jumps I make?

You can use the steps counter to see the number of jumps. If you want to have it logged into the activity file, use a Connect IQ Data Field (several of them available at https://apps.garmin.com/en-US/search?keyword=activity+steps). Or you can directly use one of the Rope Jumping apps: https://apps.garmin.com/en-US/search?keyword=rope - though you would need Instinct 2 for that. The standard Instinct 1st gen does not have any Connect IQ capability. You'd need to use Steps graph, reading the number before and after the activity from it.

everything is cool, but I have Garmin instinct, and there are no such opportunities

As I wrote - if you need to know the number of jumps, have a look at the daily Steps graph and see the difference between the end and the beginning of the activity. I am afraid that's your only option with Instinct 1st gen. I do not quite believe Garmin would retrofit Instinct with a dedicated Rope Jumping activity, but you can always try asking them: Share Ideas | Garmin

I think they won’t do it, all the more what for them, it’s easier to release a new watch with this training, but if they did it would be cool. It is a pity that there is no way to reflash them or poke around in their code, or some kind of tutorial on flashing them

You better get Instinct 2. It supports the Connect IQ API for 3rd party apps, and it is a MUCH better watch than Instinct 1st gen anyway. The basic I2 model sells now for practically the same price as Instinct 1st gen just a few weeks ago - $250, so if you manage to sell your old Instinct, you can upgrade for a bargain. Much easier than trying to hack the firmware (which you will not succeed anyway), and well worth of the money.

maybe you are right, but unfortunately, there are problems with this, if it weren’t for the war in Ukraine, then I would have done just that, I bought my Garmin instinct before the war when I had work and money. but now it’s not possible because we have a war in our country and my city is considered to be front-line, since rockets often fly to Kharkov, plus here, our services steal people and send them to death, and no matter how strange it sounds, but we have 90% of corruption out of 100% of everything that the West gives the United States and Europe are all stolen by oligarchs and deputies, and some military men make money on the death of our defenders. and I lost my job. So that's why I'm looking for some kind of costomization of this watch. and it's a pity that there are no craftsmen who at least said what code is used for software in harmines, since I'm a little versed in programming. Something like that.

Yurii said:

since I'm a little versed in programming

Well, in that case you can hack Garmin Connect with local overrides, and have it display the number of steps (jumps) during the activity. I did it in the past with the GCOverrides. I do not maintain them anymore, but the original code is still available on GitHub, so check it out. 

https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-web/214055/gcoverrides 

What you are writing about level of corruption and stolen help and other is not true! If something were stolen it would be a huge scandal  and US and Europe would refuse to help us anymore. I am Ukrainian, now we are united more than ever. We do everything to defend our country from russian aggression. I have many friends who are defending our country now. They where all trained good  for 3-6 months before sending to front lines. And thank God all of them are alive! And why are you writing this on Garmin Instinct forum??? I'm here to talk about our watches. Maybe you are russian misinformer?