In my research, I found Substack and Hashnode were good enough to get started with tech writing. Medium is fine but its too crowded and its for everyone not especially for coders.
For me, this transition took no time. It was instant, domain was propagated. In-fact I also wrote a post [made video as well] about it.
I had a very warm welcome even before posting a thing Ambassadors reached out to me on Twitter
May be you already have a good following on twitter thats why they contacted you because if you're on the board then people who follows you would get influence.
But still I genuinely appreciate Hashnode's endeavor it's good. I like it except one or two things which I can live with for now. They keep adding features and I hope they will surpass substack soon.