For what you want every meter is usable. Forget calibration, it makes a meter not better. Calibration is comparing the meter against a standard and writing down the results. So then you know that you meter shows 5,00004V when you measure 5,00000V Great, and now the best part
The specs of real meters are given for an amount of time like a value for 24 hours, a month and a year. Besides that there are other factors like temperature, humidity and pressure that will cause deviation.
And you still do not know a thing. Time will tell but only if you calibrate it regular. Calibration is about confidence and history.
If I buy a 10 dollar meter, adjust and calibrate it at 25 degrees C spot on, I use it a month, drop it some times and calibrate it again after a month at 15 degrees. I will get other results. If you do that with a Keysight of Fluke the result will often be (much) better. My Agilent came with a calibration rapport so I knew how it was set in the factory. But after 6 years of daily use it can be off a little or a lot. To know how much I must calibrate it (without adjusting) regularly. (I do that but I have my own cal lab)
But most important, what will happen if you measure a wallcontact to check if there is power and the meter shows 112V in stead of 110V. And what are the consequences if your battery is 12,05V instead of 12,1V etc
Safety is important, for me too, I know what I' m doing but because I use it a lot there is more chance I make a mistake. You have a higher chance because you may not know always what you are doing. A good meter will survive most stupid faults, a cheappy can blow up in your hand. So I' m not a fanboy of cheap meters for beginners.
That is like a car with bad brakes for a 90 year old granny . She does not drive much and not fast so she does not need good brakes ?
To know what non- safe meters are: see the huge list somewhere here on the forum. Look at the videos from joe smith, also here on the forum active.
Look the meter shootout videos from Dave to see what is important for you and how to recognize a bad meter