I bought one in LIDL a couple of years ago and never used it cos the quality was poor.
I guess you get what you pay for so one for €40 may not be top quality. There are other ones you can get (e.g. AEI digisender) that would be better quality, but also more expensive.
If it uses the 2.4GHz frequency range, which I suspect it does, then forget about it. Interference from your router or microwave will ruin the transmission. The best digisenders use the 5.8GHz band and even then transmission through walls can degrade the signal excessively. So I would say no to this offering from Aldi.
I have a similar TV sender at home. Yes, the microwave will interfere but only for a few minutes when the oven is on. I have seen no interference from low-power WiFI (router), and anyway these TV senders usually have the option to switch TX/RX channels.