I am using this app: https://f-droid.org/en/packages/eu.droogers.smsmatrix/ https://f-droid.org/en/packages/eu.droogers.smsmatrix/ You create a login for it, a

I am using this app: https://f-droid.org/en/packages/eu.droogers.smsmatrix/ https://f-droid.org/en/packages/eu.droogers.smsmatrix/ You create a login for it, and put your identity into it. When messages come in, it creates a 2-person room with itself and you, and can type your sms responses. MMS's don't work, sadly, but a few people I regularly use it with send .SMIL image attachments that get forwarded.