For some people, myself included, certain synthetic progestins can be better tolerated than natural progesterone.
Others feel better on micronised progesterone, it is very individual.
The advantages of a synthetic progestin are that it can shut down your own cycle, allowing a stable, consistent dose of estrogen to be added back. This approach works well for those with PMDD or cyclical migraine for example. Basically you get to ride a monorail instead of a roller coaster.
Likewise a synthetic progestin can keep you bleed free, which no amount of micronised progesterone is likely to do if you are not yet menopausal.
Progestins also offer superior protection against endometrial hyperplasia.
Now some people, particularly on social media think absolutely everyone should be on micronised progesterone because it does have a slightly more favourable metabolic profile and a slightly lower breast risk, however in my opinion neither of these are worth sacrificing your quality of life for because the real world difference in health outcomes is marginal.
So the benefits of using double dose desogestrel instead of the progesterone, plus your estrogen of choice, would (hopefully) be feeling more like you were on a combined pill taken continuously, with no bleeding and no hormonal ups and downs.
The combined pill means not only do I avoid having to take micronised progesterone, it also stops my ovaries from releasing any - no ovulation, no progesterone!
Long term ovarian suppression like this also reduces ovarian cancer risk, which is why I originally went on the pill 16 years ago.
If you have been on the mini pill in the past with desogestrel you will know whether you tolerated it or not.
You are right that it may affect your mood without estrogen but I wouldn't really recommend anyone take it without estrogen, except perhaps someone young with no complex needs who just wanted birth control and no other options were available or suitable.
You can alternatively take single dose desogestrel daily plus 100mg progesterone daily with estrogen, but this is a lose-lose situation in my opinion as it doesn't avoid the progesterone, is less likely to achieve amenorrhoea and has not been shown to reduce ovarian cancer risk.