For anyone else who's also wondering about browser support:

(Stats updated July 2022)

loading="lazy" 89% (caniuse.com) Safarai finally supports this in 2022. Support jumped up to 89% from 73% since writing the comment.

<datalist> 97% (caniuse.com) Almost all browsers (even IE!), lots of partial support though

<picture> 97% (caniuse.com) Everywhere except IE and Opera. `img` fallback support works everywhere

http-equiv="refresh" 65% (caniuse.com) Okay, this is the weirdest browser support I've ever seen. Currently, this is supported by ALL desktop browsers including IE and Safari. IE since 2013. However, Chrome and Edge only started supporting in 2021, Safari and Opera since 2020. Shoutout to Firefox for supporting this since 2006.

Note: http-equiv="refresh" is discouraged since it breaks WCAG 3.2 Guideline: Make Web pages appear and operate in predictable ways.