Hi OP. I have read your posts but not the full thread.
I am a child psychologist.
First off, he is a pandemic baby. We know many only and oldest children who were born or babies in lockdowns have delayed interactive and social skills. They have missed out on socialisation very early on. They need more opportunities for peer based play, not less, because they struggle. Play is where children learn skills of sharing, negotiation, turn taking etc - these are not innate.
Second, having delayed language skills does make toddlers more frustrated and harder to manage. He should be able, at 2.5, to speak in short sentences such as "me want biscuit" or "mummy do it", and he should be able to follow short instructions such as "go get your shoes and your coat" or "would you like an apple or banana?". If not, use visuals to support you - hold up the apple and banana as you offer them, ask him if he wants the blue cup or red cup whilst holding both, that sort of thing.
Play lots of turn taking games - initially rolling a ball back and forth between you, or blowing bubbles and asking if he wants more - getting him to say "more" - plus rhymes and songs with actions that he can anticipate as familiar rituals - Humpty Dumpty with him sat on your lap, while you hold his hands, when you say "fall" open your knees so he slips between them. Row your boat. Round and round the garden. Hide and seek where you hide in an easy place and leave "clues" such as giggling when he's near or have your feet sticking out from behind a curtain. Cover him up and wonder aloud where he's gone. These types of games are so simple but really effective for turn taking, cause and effect, anticipation.
Mostly, don't worry. Kids aren't two forever. Even if he does turn out to have a developmental issue, he will grow change and develop. My eldest as an autistic 20 year old is very different from when he was an autistic 12 year old, or an autistic 6 year old, or an autistic toddler. This too shall pass.