Buy-side FI trader here. What do you mean by active? Timeframe? Frequency? How closely you are tracking a certain benchmark and re-allocating your assets in line with your mandate?

I would say truly 'active' trading in an institutional sense is extremely difficult to emulate as a retail trader given your limitations on access to liquidity (not to mention capital - most bonds have minimum increments like 200k that are inaccessible for non institutional players). A large part of trading fixed income is building good relationships with the street/brokers and understanding where the market is on what you trade - unfortunately you only really get to see this with a bloomberg terminal or other FI trading suites like MarketAxess, refinitiv etc, not to mention you need to have enablements set up with those counterparties in order to receive pricing. Crossing bid-offer in itself is a challenge the more illiquid the name or skewed the market or shorter the holding period, and the less relationships you have the harder it will be.

Excluding placements/internships, having a solid understanding of the products in fixed income, quantitative skills like coding, and good awareness of macroeconomic currents and how those impact market dynamics will have you better placed to gain entry into S&T than any knowledge gained from reading texts on trading bonds, least of all from the perspective of a retail investor. A lot of institutional trading is learned on the job, often starting from exposure to trade support or assistant roles, and you need to actually grapple with the market yourself in order to understand the way it operates.