Two quick data points from the past fortnight:

In Thailand (Bangkok only) we used dtac "Happy Tourist 5G" eSIMs purchased through Airalo. Never lightning fast but consistently available and always more than adequate for maps, Grab, messaging and news.

After landing at SIN I tried to get a 12 SGD M1 5G tourist eSIM but the counter I asked at didn't have that option, so I went into town without local service. I then discovered that M1 doesn't currently have a flagship store on/near Orchard, so just bought a 12 SGD Singtel 4G eSIM online. Activation was easy (see frappant's post above) and service was almost always good to excellent.