As I start some of these lessons, it shows," this unit supports Mynediad Unit 2 and Welsh for the Family Unit 1." Are these texts that I should purchase to go along with this course? I cannot find any information on them, and feel like I missed a step somewhere. Thank you for your time answering this.
The Duolingo course has been developed around the patterns and vocabulary in the Welsh for adults courses 'Cwrs Mynediad' (Entry), 'Cwrs Sylfaen' (Foundation) and 'Cymraeg i'r Teulu (Welsh for the family). There are various support materials available.
Here's the link to an online version of the course in the USA. It's only the South Wales version, but better than nothing for free. Remember this is copyrighted material and if you live in the UK you should really buy them (you can also get them internationally too).https://cls.byu.edu/welsh/BYU_Cwrs_Mynediad.html
The course book material for the same level of course (WJEC Mynediad and Sylfaen) is available for free if you look on the internet for 'cwrs sylfaenol Ceredigion' and look for links to y Bont or Aberystwyth, etc.
It is produced by the Welsh for Adults centre run by Aberystwyth University. It is very clear about showing how the west Wales dialect, Dyfedeg, relates to a more generic colloquial Welsh.
No, they are not essential to follow the Duolingo course but there are several other on line courses available from Bookshops and if you are also following these two particular courses then it is saying that this skill supports them.