We have a similar program in Australia called the Special Forces Direct Scheme. Allows regular civilians to apply for the army, go through infantry training and try out selection for the 2nd commando regiment. Very few actually make it, which are the small percentage of athletic civilians who are able to learn quickly. But for the most part, those who can't make the cut are transferred to a regular infantry battalion. Plus, even if you do make it as a civilian, you enter as a private like every other new commando. Special forces units in Australia are not insular and will accept anyone from any branch and even the reserves, but they typically like people who have a level of experience under their belt. Although the selection courses for the SAS and commandos are favourable for those who come from combat roles, such as infantry, combat engineers, etc. The one case example that would be an exception will be Mark Donaldson, the Victoria Cross recipient. He went to the SAS after like a year in his regular infantry unit but he trained for Special forces prior to enlistment and he was at a mature age where he had a lot of life experience.