And does there have to be any Christmas tree, maybe a wreath of twigs?

Most considerations are only from the point of view of "what is more convenient for me or what I like more". I think that from the perspective of our environment, both choices are not good.

An artificial Christmas tree may be economically profitable for us (1 purchase for several years), but many artificial compounds are released into the environment during its production before it is used. Later, it goes to the sun, where not everything will be recovered and it will lie there for a few years, not necessarily with a positive impact for the place where it ends up (microplastic and other artificial compounds from decomposition). The impact, which is not necessarily beneficial (apart from the joy of Christmas and the salesperson's income), will last for years, although after closing the dumpster, most will not think about what to do next.

A live Christmas tree seems to be more "ecological" (but what does that actually mean - a topic for another question), then if it comes from a plantation - it is an area of the environment that has been changed and adapted for specific production (mixing soil, adding artificial fertilizers, removing plants that would naturally grow there). To this you have to add (as in the case of an artificial one) other things, because they need to be transported, packed, etc. A natural Christmas tree thrown away will not cause any damage to the environment, because it will be a place of life for many organisms. But if we throw away 1000 such Christmas trees in one place, we will change this place.

There is also an option that I use, digging a small tree or buying a seedling and keeping it in a pot for 2-3 years and planting it back into the forest. But will we plant them in their natural conditions or wherever we feel like. But again, 1 tree will not change much, but 1000 is already a spruce forest.

Such considerations about human action for pleasure for a few days, and how many such pleasures do we give ourselves?

¿Árbol de Navidad vivo o artificial?