I have a winning no limit holdem friend who is playing low stakes online never studied with solver. I am looking to buy him a gift for starting to learn using solvers. I play plo and i have no touch with the no limit world. Is there any course which goes over spots and explaining how and why solvers are taking certain lines? Example 100bb big blind against button, solver choose to donk on 543 rainbow, i need the course to explain exactly why the solver is taking this action and what we have to look in order to build our range in a similar spot we never studied. I am looking one course for beginner level introduction into solvers and one for intermediate level, price not an issue for the gift. I came across a course from 2 cardconfidence but it seems impossible to cover even a small percentage of what i am looking into a 4.5hr course

Jonathan Little's cash game masterclass might be a good option. It starts with the basics then progresses through preflop spots, a wide variety of different flops, turns, rivers, etc. with lots of solver charts.

I think you can buy it as a standalone product, but I'm not sure about the price. It's also available with a poker coaching premium membership, so purchasing him a month or two membership might be an option. I think by default the membership auto renews, but I'm sure if you emailed them and told them you wanted to purchase a limited subscription as a gift they should be able to help you.

Jonathan little's coaching are way too low of a quality. My friend is winning nl50 at ps at good winrate, he is familiar with preflop ranges. I need something focussed on what described above for postflop. He isnt confident to move up unless do some courses i mentioned above, he is playing nl50 for long time. Please recommend only decent products

I was thinking buying avecedo's and janda's book but he is the video type of guy

You did say "beginner level introduction to solvers" in your initial post, and you didn't mention that he was beating NL50. Anyway I wouldn't write off JL's site so easily. His paid content is better than his free content, which is mainly aimed at recruiting newer players. His site also gives you access to other minds, including quite a bit of content from Michael Acevedo.

Gareth James might be a good option for someone around the skill level of where your friend is at. The content I have seen from him is more tailored to the nitty gritty process of dialing in ranges and plugging leaks for online play.

If you think Jonathan Little Pokercoaching site is too low quality for what you're describing, you probably aren't actually familiar with what's on the site.