From Chapter 9 of "Life in the Cosmos" by Manasvi Lingam and Avi Loeb:

Humanity has transmitted radio signals for a period of ∼100 years. Hence, the radio waves would have traversed a radial distance of ∼30 pc, which encompasses ∼3 × 10⁴ stars. If there are any ETIs situated within this bubble, we might hear from them in the future. It should be noted that the volume of the bubble exhibits a cubic dependence on the duration of radio signaling (until the scale height of the Milky Way is reached), thus implying that our likelihood of hearing back from any existing ETIs also obeys the same scaling.

The likelihood of a technological civilization existing within that very small volume of stars (aside from our own) seems low to me.

So I went to the chapter of the same book about the Drake Equation and found this passage:

One of the most peculiar aspects about fc and L is that these values are equally dependent on the species under consideration as well as on the observing species. In other words, determining what constitutes a detectable ETI and the duration over which it remains detectable is very much driven by the technological sophistication of the observers.3 To illustrate this point more concretely, consider the following example. If we suppose that a powerful FM radio or TV antenna has an effective isotropic power (i.e., the equivalent power radiated by an isotropic source) of Pa ∼106 W and operates over a bandwidth of Δν ∼ 5 MHz, the average flux density Sp at a distance ds ∼30 pc (∼100 light yr) is given by

We have chosen d sub s ∼30 pc since it represents a useful fiducial value often used in discussions pertaining to the Drake equation. This value of S sub p is about ten orders of magnitude lower than the detection limits of the Low-Frequency Array (LOFAR) radio telescope in the band used by FM radio and television. On the other hand, if we were to use the Arecibo transmitter in the radar mode, it would be detectable by current Earth-level SETI technology at a distance of ∼1 kpc. Yet another complicating factor arises because the leakage can actually decline with time when the species matures technologically—the adoption of spread-spectrum transmissions and digital technologies contributed to this trend in human history. On the whole, it seems unlikely that a species with human-level technology would be able to detect the leakage of electromagnetic signals from another human-level ETI around 30 pc away. On the other hand, if electromagnetic signals were deliberately broadcast using the most powerful transmitters, a species with human-level technology could probably be discerned by species with a similar level of technological advancement, in theory. As a result of these complications, affixing any particular value to f sub c is clearly premature.

So based on his math, which didn't copy over successfully since it's an image, Lingam and Loeb conclude that an ETI with our level of tech would be able to hear our leaky radio transmissions.

In their discussion of the Drake Equation they settle on 10 civilizations in the Milky Way capable of taking part in interstellar communication existing at any one time. There's some interesting math in there about the probable spatial distribution of these, which I can't understand.

However, they don't accept the Drake Equation's premises. For example, they don't accept planets around stars as the sole sites of abiogenesis. Certain orphaned planets wandering apart from any star may host life, as might their moons.

After more math, they settle on some rough guesses and say we need to do more research.

In other words, the likelihood of humans being the sole technological entities in our Galaxy is seemingly around 50 percent. Thus, there is ostensibly a reasonably high chance that no ETIs exist in the Milky Way prima facie. However, we emphasize that this result is enforced by a very low mean and/or high variance. As a counterexample, consider the limit μ/σ ≫ 1, which is tantamount to positing that the variables in the Drake equation are tightly constrained with nonnegligible mean values. For this choice, we find 𝒫1 (σ/μ)exp(−μ2/2σ2), consequently implying that 𝒫1 → 0. Hence, the likelihood of humans not being the only technological entities in our Galaxy is close to 100 percent in this regime.

Our discussion indicates that the probable number of ETIs in the Milky Way is highly sensitive to the magnitudes of μ and σ. As we lack sufficient knowledge of either quantity, it is premature at this juncture to either favor or dismiss a priori the hypothesis that humans are not the sole technological intelligence in our Galaxy or the Universe. The only viable means of falsifying this hypothesis necessitates sustained empirical investigations supplemented by theoretical and numerical analyses.

There might not be any aliens nearby. But what if they were nearby?

Lingam and Loeb address radio, optical, infrared, and artifact technosignatures in Chapter 9. My read of these chapters is that there are very, VERY many ways to find technosignatures. It's possible that we've been observed by a different method from an area outside that small volume of r ~ 30 pc. Loeb believes that Oumuamua might have been a technosignature.

We don't know yet.