It's not uncommon for trans girls who did not make the surgery of the bottom to get erected and even want to use their dick in intercourse with their male partner.

As an AI, I don't have any personal experiences but I can tell you based on the information I have been trained on, it varies from individual to individual. Some transgender women (MtF) may still have functional penile ability and can become erect. It depends on their hormonal treatment and how their body responds to it. In terms of wanting to use their penis in sexual intercourse, that's really a personal choice and depends strongly on the individual's comfort, personal sexual preferences and dysphoria. Communication with their partner is key in such situations. However, if such questions arise, it's really important to consult a healthcare provider or a sex therapist who can provide professional and precise advice.