Can I use
?

XHTML served as application/xhtml+xml

- LS

A strict form of HTML, and allows embedding of other XML languages

Chrome

  1. ✅ 4 - 133: Supported
  2. ✅ 134: Supported
  3. ✅ 135 - 137: Supported

Edge

  1. ✅ 12 - 133: Supported
  2. ✅ 134: Supported

Safari

  1. ✅ 3.1 - 18.2: Supported
  2. ✅ 18.3: Supported
  3. ✅ 18.4 - TP: Supported

Firefox

  1. ✅ 2 - 135: Supported
  2. ✅ 136: Supported
  3. ✅ 137 - 139: Supported

Opera

  1. ✅ 9 - 116: Supported
  2. ✅ 117: Supported

IE

  1. ❌ 5.5 - 8: Not supported
  2. ✅ 9 - 10: Supported
  3. ✅ 11: Supported

Chrome for Android

  1. ✅ 134: Supported

Safari on iOS

  1. ✅ 3.2 - 18.2: Supported
  2. ✅ 18.3: Supported
  3. ✅ 18.4: Supported

Samsung Internet

  1. ✅ 4 - 26: Supported
  2. ✅ 27: Supported

Opera Mini

  1. ✅ all: Supported

Opera Mobile

  1. ✅ 10 - 12.1: Supported
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ✅ 2.1 - 4.4.4: Supported
  2. ✅ 134: Supported

Firefox for Android

  1. ✅ 136: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ✅ 3: Supported

The XHTML syntax is very close to HTML, and thus is almost always (incorrectly) served as text/html on the web.

Resources:
Information on XHTML5
Wikipedia
Sub-features:
XHTML+SMIL animation