Can I use
?

XHTML+SMIL animation

- UNOFF

Method of using SMIL animation in web pages

Chrome

  1. ❌ 4 - 142: Not supported (but has polyfill available)
  2. ❌ 143: Not supported (but has polyfill available)
  3. ❌ 144 - 146: Not supported (but has polyfill available)

Edge

  1. ❌ 12 - 18: Not supported
  2. ❌ 79 - 141: Not supported (but has polyfill available)
  3. ❌ 142: Not supported (but has polyfill available)

Safari

  1. ❌ 3.1 - 26.1: Not supported (but has polyfill available)
  2. ❌ 26.2: Not supported (but has polyfill available)
  3. ❌ TP: Not supported (but has polyfill available)

Firefox

  1. ❌ 2 - 144: Not supported (but has polyfill available)
  2. ❌ 145: Not supported (but has polyfill available)
  3. ❌ 146 - 148: Not supported (but has polyfill available)

Opera

  1. ❌ 9 - 121: Not supported (but has polyfill available)
  2. ❌ 122: Not supported (but has polyfill available)

IE

  1. ❌ 5.5: Not supported
  2. ◐ 6 - 8: Partial support
  3. ❌ 9 - 10: Not supported
  4. ❌ 11: Not supported

Chrome for Android

  1. ❌ 142: Not supported (but has polyfill available)

Safari on iOS

  1. ❌ 3.2 - 18.6: Not supported (but has polyfill available)
  2. ❌ 26.0: Not supported (but has polyfill available)
  3. ❌ 26.1: Not supported (but has polyfill available)

Samsung Internet

  1. ❌ 4 - 28: Not supported (but has polyfill available)
  2. ❌ 29: Not supported (but has polyfill available)

Opera Mini

  1. ❌ all: Not supported (but has polyfill available)

Opera Mobile

  1. ❌ 10 - 12.1: Not supported (but has polyfill available)
  2. ❌ 80: Not supported (but has polyfill available)

UC Browser for Android

  1. ❌ 15.5: Not supported (but has polyfill available)

Android Browser

  1. ❌ 2.1 - 4.4.4: Not supported (but has polyfill available)
  2. ❌ 142: Not supported (but has polyfill available)

Firefox for Android

  1. ❌ 144: Not supported (but has polyfill available)

QQ Browser

  1. ❌ 14.9: Not supported (but has polyfill available)

Baidu Browser

  1. ❌ 13.52: Not supported (but has polyfill available)

KaiOS Browser

  1. ❌ 2.5: Not supported (but has polyfill available)
  2. ❌ 3: Not supported (but has polyfill available)

Internet Explorer supports the W3C proposal HTML+TIME, which is largely the same as XHTML+SMIL

Resources:
Wikipedia
JS library to support XHTML+SMIL