SponsorBlock is available on just about every type of device these days -- works perfectly on Android with YouTube ReVanced. The options on iOS are naturally a bit more limited, but apparently it's possible on a jailbroken device (or through some other slightly-janky methods on non-jailbroken devices): https://github.com/ajayyy/SponsorBlock/wiki/iOS

It works on Firefox on Android as well, as do many other FF extensions. It won't work on a fruit phone [1], the Firefox version you can get there is lobotomised because the fruit factory is afraid a full-feature browser not under their control will eat into their app store margins.

[1] https://support.mozilla.org/en-US/questions/1486487