I was able to provision a Three HK prepaid roaming eSIM on a Google Pixel 3a without any issues.

Three's roaming plan is 10 days at 500MB/day, throttled to 128kbps after you hit the daily quota. You can buy it directly from Three's web site for HKD $138 (USD $17.58).

Roaming coverage countries
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APAC: China, Macau, Taiwan, Japan, South Korea, Singapore, Malaysia, Thailand, Philippines, Vietnam, Australia
N. America: USA, Canada
Europe: United Kingdom, Italy, Sweden, Ireland, Denmark, Austria, France