I feel like the episodes themselves are meant to be clear indications of what a Pokémon Master is, and that it is a broad term regardless.
Episode 1 saw Ash selflessly save a Pokémon in trouble, a Legendary Pokémon no doubt, who very much did not want to be around humans. Despite that Ash put himself on the line without thinking and was able to save it - thus gaining some form of trust with a Legendary Pokémon - this isn't something new to the anime but it probably is one of the more outstanding criteria for being a Master. Being able to bond with even the most untrusting Pokémon. This is something that is done in movies quite often, but as the movie canon is shaky and always seems to be overly heightened, I prefer seeing them in the anime.
Episode 2 is probably where I find it to be a bit of a reach, although it was solely to reintroduce Misty and so on, I do feel that Misty beating Ash to catch a water-type Pokémon that she very much wanted was intended to teach Ash that even though he's the PWC he cannot win every battle (Even a human to human battle over a Pokémon) and that sometimes a certain Pokémon belongs with a certain trainer. Taking a sea dwelling water type away from an aspiring Water-type master is something Ash had to learn couldn't happen, no matter how good his standing in the ranked community is. Again, it probably is a bit of a reach, and was just meant to be light hearted but it was a subtle message, I feel.
Episode 3 showed Ash selflessly defending his friends and wild, random Pokémon (Again) - Going out of his way to help find Brock, calm down the wild Hatterene and also protecting the Hatenna. This episode could have been a little more interesting and diverse, seeing Brock/Misty again is great and introducing a new dynamic through Cilan is also great - but it was disappointing not to see Ash use any reserves. But again, I do think it adds to the overall Pokémon Master development.
And finally episode 4 is very similar to 1 and 3 in terms of Master development, but it showed Ash actively working together with a willing wild Pokémon - showing he can convey his trust over quite well and help Pokémon master their skills and abilities very quickly, all whilst working together with his Pokémon and companions.
As I said, I do think some points are a reach, but I think the aim of this series is to subtlety show the audience that whilst the criteria to become a Pokémon Master is so broad (and vague) that Ash is able to meet and exceed it when it is laid out. The episodes do come across as filler, but I think that's generally because there is no bigger goal. It's more so Ash learning what it is he needs to do in order to reach his goal. But the "filler" episodes, are high class filler episodes.
After Journeys it's nice to just see Ash travelling with companions again using his reserves, I think there was no better way of having it end. Having a mini-series full of high intense battles would feel pointless, because how would it be deemed who takes priority? There are a lot of people Ash has lost to, some unjust, some not, but an 11 episode series cannot fit them all in. And TPC seem eager to have everything (Merch, anime, TCG, games) all sync up. A major misstep was not having a Galar saga, as a lot of characters from the games felt flat and weren't able to come alive in the anime.
I do have a small theory that Ash will doubt what makes a Master, we haven't had that scene from Gary yet from the initial preview where he's questioning Ash's motives - I do think that will lead to some minor-doubt which will end in Latias being caught in front of everyone in the final episode (I do think the final episode will be all companions at Oak's ranch where Latias shows itself again)
Latias has been following Ash since Episode 1, and it is v obviously foreshadowing a capture.