Answer is:
No
I did not manage to send directly from Mikrotik, because "fetch" tool does not support sending files. I managed to send using Raspberry Pi:
Generate SSH keys on raspberry Pi and its upload public key to each router. Then pretty much use this bash script:
#!/bin/bash
ROUTER=$1
TITLE=$2
SSHUSER="admin"
SSHIDENTITY="~/.ssh/mikrotik"
TELEGRAMCHATID="1234567890"
TELEGRAMAPIKEY="0000000000:AAAAAAAAA-bbbbbbbbbbbbbbb-cccccccccc"
OUTPUT=$(ssh -i "$SSHIDENTITY" "$SSHUSER@$ROUTER" "/export")
RES=$?
if [[ $RES -eq 0 ]]; then
TMPFILE="/dev/shm/export_${TITLE}_$(date +%Y%m%d)"
echo "# Address: $ROUTER" > $TMPFILE
echo "#" >> $TMPFILE
echo -e "$OUTPUT" >> $TMPFILE
curl -s -F "chat_id=$TELEGRAMCHATID" -F "document=@$TMPFILE" https://api.telegram.org/bot$TELEGRAMAPIKEY/sendDocument > /dev/null
rm $TMPFILE
fi
Then in crontab:
# Backup Mikrotik routers
0 2 * * * /storage/tasks/others/mikrotik-backup.sh aaaaaaaaaaaa.sn.mynetname.net name1
0 2 * * * /storage/tasks/others/mikrotik-backup.sh aaaaaaaaaaaa.sn.mynetname.net name2
0 2 * * * /storage/tasks/others/mikrotik-backup.sh aaaaaaaaaaaa.sn.mynetname.net name3
EDIT: Don't like or don't have Raspberry Pi? Get the cheapest
Linode instance then and host such script on it. 5 dollars per month for the cheapest instance AFAIK + you can do other stuff on it.