Good day,
currently (and you always have to keep in mind, that this may change any minute) the encryption standard used for solely encrypting the home folder, is provided directly by the Linux kernel and is said to be rather safe, if you use a proper pass phrase. However, you’ve to keep in mind that, of course, anything not saved in the home folder, isn’t encrypted. Depending on how you use your system, this can lead to an attacker gaining a lot of information about you from the things which, for example are stored in the / part of your installation. That is one of the reasons, why, if possible, a complete disk encryption is definitely to be recommended over only encrypting the home folder. Furthermore, since it is possible to, at least, boot the system, the attack surface is considerably bigger over encrypting the whole drive, especially if you’ve things like “guest accounts” activated. Now, I don’t really know, what you mean by your last question. Are you asking whether someone may see, what you did, last time you used the pen drive? Because, like I’ve said before, all the unencrypted parts already may tell someone a lot about you. Just look at all the folders which are, in the file tree, “higher” than your user folder and you may see for yourself, what someone may be able to get out of the stick, with the encryption still intact and untouched. Furthermore, 10 characters, may seem a lot, but it’s not really that long, compared to “proper pass phrases”, which may have up to 40 signs and are often easier to keep in mind. If you need some inspiration on what kind of pass phrases are considered “proper ones”, I recommend this video, in which John Oliver and Edward Snowden demonstrate it, in the best way possible: https://www.youtube.com/watch?v=yzGzB-yYKcc
Have a nice day,
Ego