I'd like to be able to enter combining diacritics U+0300 and U+0301

Sometimes I want to enter arbitrary IPA strings into websites from my phone. I've tried finding a privacy-respecting way to conveniently do this and the best way I've found so far is to use the app Unicode Keyboard by Tim Wunderlich, available on the Google Play Store, and enter the code point for the IPA letters or diacritics I want. This works in every other app, but in Firefox, there are two characters I can't enter this way - the combining grave diacritic U+0300 and the combining acute diacritic U+0301. Even other combining diacritica work. I like researching and talking about linguistics and conlanging online, and sometimes this involves using those diacritics to mark tones. This is such an odd specific incapability for Firefox to have but it has persisted, since at least as far back as 2024. I've just had to enter those diacritics in another app and copy&paste them in. I can enter the diacritics directly as keyboard input in Firefox on Windows and GNU/Linux.