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 - 146: Supported
  2. ✅ 147: Supported
  3. ✅ 148 - 150: Supported

Edge

  1. ✅ 12 - 146: Supported
  2. ✅ 147: Supported

Safari

  1. ✅ 3.1 - 26.3: Supported
  2. ✅ 26.4: Supported
  3. ✅ 26.5 - TP: Supported

Firefox

  1. ✅ 2 - 149: Supported
  2. ✅ 150: Supported
  3. ✅ 151 - 153: Supported

Opera

  1. ✅ 9 - 127: Supported
  2. ✅ 131: Supported

IE

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

Chrome for Android

  1. ✅ 147: Supported

Safari on iOS

  1. ✅ 3.2 - 26.3: Supported
  2. ✅ 26.4: Supported
  3. ✅ 26.5: Supported

Samsung Internet

  1. ✅ 4 - 28: Supported
  2. ✅ 29: 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. ✅ 147: Supported

Firefox for Android

  1. ✅ 150: 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