To determine if "REN - REDES ENERGÉTICAS NACIONAIS, SGPS, S.A." is suitable to issue hybrid bonds, we can evaluate its financial health, sector, and capital structure based on the provided annual report data for 2022:

1. **Sector and Business Model**: REN is the operator of the national electricity and gas transmission networks in Portugal. Utility companies with regulated, predictable, and highly stable cash flows are prime candidates for issuing hybrid bonds. They often use these instruments to fund large capital expenditures without negatively impacting their credit ratings, as rating agencies typically treat hybrid bonds partially as equity.

2. **Size and Scale**: The company is a large-cap enterprise with total assets of €6.45 billion and total equity of €1.52 billion as of the end of 2022. This extensive scale provides the necessary foundation to attract institutional investors in the hybrid bond market.

3. **Profitability and Cash Flow**: REN is consistently profitable, reporting a net profit of €111.7 million and an operating profit of €239.7 million in 2022. More importantly, its cash flow from operating activities was exceptionally strong at €613.5 million, ensuring it has robust liquidity to comfortably service the higher coupon payments typically associated with hybrid debt.

4. **Capital Structure**: The company has long-term borrowings of €1.69 billion and current borrowings of €638.9 million. This presents a moderate leverage ratio typical for a regulated utility. Issuing hybrid bonds would allow REN to raise capital for energy transition investments while protecting its senior debt ratings and maintaining its healthy balance sheet.

Given its status as a large, stable, and profitable national utility company with strong cash generation, REN perfectly fits the profile of an ideal hybrid bond issuer. 

<answer>Strongly Suitable</answer>