Digital modes are allowed over FRS radio, without a license. Here is a test I performed, sending text over an unmodified radio using the data mode called BPSK31.

https://kolektiva.social/system/cache/media_attachments/files/116/099/165/793/889/140/original/12fed77c04435ef1.mp4

backup: https://cdn.masto.host/mastjohn1126com/media_attachments/files/116/099/159/162/674/108/original/428480a0527515b5.mp4

From the FCC rules

§ 95.531 Permissible FRS uses. "FRS units may transmit digital data" ... "containing a brief text message"

A text message that is "brief" is a vague specification, defined without a numerical value of time or length of text. So it is a subjective judgment on how long the transmission may be.

The data modes allowed are also not defined. The FCC makes no mention of “prohibited digital modes”. So I assume any digital mode may be sent over an unmodified FRS radio with a voice transmission.

FRS units may be used for one-way communications that are emergency messages, traveler assistance communications, voice pages or brief equipment tests."

Equipment tests are also allowed over FRS, as a one-way broadcast, without any intended second party.

And in an emergency, any mode of transmission is allowed over any radio, even without a license, if it is for "immediate safety of human life or protection of property".