Assuming you are in the US or want a US number, I recommend Google Voice and turn on spam protection.
While the SMS integration is going away soon, you will still be able to use (I think) SMS from within the app and while the terms of service disallow automation, my understanding is that is mostly only for outgoing texts (they don't want Google Voice users spamming the world) rather than incoming (I don't see why Google Voice would be against you doing whatever you want with the texts you receive).
I suspect the reason why carriers allow these spam calls and texts is they make money from all calls and texts and have no incentive to fix things.
I use SMS-via-email very frequently, and was rather worried. Thankfully that will stay.
SMS forwarding to a local number's SMS hasn't been possible for me anyway, because my local number is not in the US. At one point I had a setup with Google Calendar forwarding my emails to SMS, but that got shut down in 2019 (to my dismay).
While the SMS integration is going away soon, you will still be able to use (I think) SMS from within the app and while the terms of service disallow automation, my understanding is that is mostly only for outgoing texts (they don't want Google Voice users spamming the world) rather than incoming (I don't see why Google Voice would be against you doing whatever you want with the texts you receive).
I suspect the reason why carriers allow these spam calls and texts is they make money from all calls and texts and have no incentive to fix things.