of course you know about GAS. (Guitar Acquisition Syndrome). You can likewise get G(e)AS (Gear Acquisition Syndrome. .
A lot depends on the quality of your on board pre-amp, and the setting where you gig. There would be three different scenario’s to consider:
(1) you only play at home
(2) you play through the PA system.
(3) you play through an Amp suitable for an Acoustic. (e.g. an AER, or a Schertler etc.)
If you only play at home, in case you don’t already do this, start recording yourself, and equip yourself with an audio interface and a DAW. That will help your playing immensely. Any effects you buy subsequently including loopers, are easily accommodated by that setup.
In case you play through the PA system, it may be worthwhile to invest in a DI box, which connects to the mixer using an XLR cable. A lot of DI boxes have some controls on them, such as an analog equaliser, or even more advanced electronics that try to emulate the ‘pure’ acoustic signal, so as to improve on the sound quality of the piezo under saddle pickups of acoustics. Look at LR Baggs for very high end offerings on this.
You’ll have to experiment with that, you could do that at home using an audio interface if you are already in home recording, which is in anyway ‘the thing to do’ if you want to record yourself in your guitar learning. Mind you, many of the higher end acoustics already have very powerful pre-amps on board, combining microphones and under saddle pickups, and you would not really need the DI box.
Obviously there are very good loopers, and they are good fun, and they are great for getting some percussive effects and rhythm pieces in so you can add some solo leads and riffs on top of that. At home however you then you would benefit a lot of having the acoustic amp, rather than the audio interface / headphone combo to practice with it.
Which brings me to (3), if you would be gigging and bring your own Amp, in which case you would need to have both your microphone for singing and the guitar inputting into the acoustic amp. Then you would need the typical singer songwriter, pub-corner/bookshop/busker set up, with a microphone, stander, acoustic amp etc.
There are some specialised pedals for singer songwriters, providing not only effects for the acoustic (looping, reverb, on-board tuner etc.) as well as for the singer (harmonise etc.). There you will be looking at something around 400 EUR.
I hope this helps you.