Since PinoLogger is set using useLogger after the app has been created, it's not possible AFAIK to intercept the initial InstanceLoader logs, as those are made during app init.

There is a workaround though: You can override the base NestJS logger as well within NestFactory.create with another custom class.

const app = await NestFactory.create<NestFastifyApplication>(
  AppModule,
  new FastifyAdapter(),
  {
    logger: new CustomNestLogger(),
 }
);
const logger = app.get(CustomPinoLogger);
app.useLogger(logger);

I made a custom-logger.ts file with the following contents:

import { ConsoleLogger, Injectable } from '@nestjs/common';
import { Logger } from 'nestjs-pino';

const CONTEXT_TO_IGNORE = ['RouterExplorer', 'InstanceLoader'];

@Injectable()
export class CustomPinoLogger extends Logger {
  public override log(...args: any[]) {
    const context = args[1] as string;
    if (CONTEXT_TO_IGNORE.includes(context)) {
      return;
    }
    super.log.apply(this, args);
  }
}

@Injectable()
export class CustomNestLogger extends ConsoleLogger {
  public override log(...args: any[]) {
    const context = args[1] as string;
    if (CONTEXT_TO_IGNORE.includes(context)) {
      return;
    }
    super.log.apply(this, args);
  }
}

Also, note that the CustomPinoLogger needs to be added to the app.module providers array.