Provide a disposable number and e-mail address. For example, use a pre-paid 2nd SIM for this purpose and discard it after a year (mine gets cancelled after 6 months of no use). With regards to e-mail there's various solutions for that.
I wholeheartedly recommend masking your email and phone number with blur/abine. Every website I have an account with literally thinks I have a different email address. You can also mask your credit card number but you have to pay extra for it so I don't.
My only regret is that I do still get the spam texts and calls. I am thinking that I should somehow make my current number a google voice number or something so that there can be just an automated system that asks them to press any number to connect. Something that simple would stop 100% of my spam calls because they are all robocall recordings.
I think that, as long as you're okay with paying for a service, it can be fairly easy. It's when you want to do it all yourself that you have to be an OPSEC professional. There is plenty of middle ground of paying someone who knows what they're doing to provide the ability to better mask who you are and make it expensive for someone to spam you. Make them waste their time talking to your automated answering service for a change.
But yeah, it's frustratingly complicated. Some of this stuff just seems like it should be a built-in feature of modern telecommunications. My cell provider should give me the ability to present an automated message for free, and at least block numbers... mine doesn't even let me block numbers, I have to do it at the phone level so I still get voicemail messages. That kind of stuff seems like it should be considered basic service.
spamgourmet.com has been around for years (two decades at this point I think?) and does give you disposable emails without the need to configure anything about the alias before using it.
